What is the legal definition of an addendum?

An addendum is a document that adds new terms or information to an existing contract without altering the original text, making it a practical tool for including supplementary details like additional deliverables or updated schedules after the initial agreement has been signed.

What is the legal definition of an amendment?

An amendment is a formal change that modifies, deletes, or replaces specific provisions within an existing contract, requiring the same level of consent as the original agreement and resulting in a revised version of the original terms rather than a separate addition.

What is the main difference between an addendum and an amendment?

The main difference is that an addendum adds new terms without changing existing ones, while an amendment alters or replaces current provisions, so an addendum expands the contract's scope and an amendment revises its core content.

Which is better for a real estate purchase agreement: an addendum or an amendment?

An addendum is better for a real estate purchase agreement when you need to add new conditions like a home inspection contingency or seller credits, whereas an amendment is better when you must change the purchase price, closing date, or property description already written in the contract.

Does an addendum cost more than an amendment to prepare?

An addendum typically costs the same as an amendment, often ranging from $150 to $500 for attorney preparation, but the price depends on complexity and location rather than the document type, so you should budget based on the specific changes needed.

Is it safe to use an addendum instead of an amendment for a contract change?

It is safe to use an addendum instead of an amendment only if you are adding new terms, but it is risky if you intend to change existing terms, as using the wrong document can create conflicting provisions and lead to legal disputes over enforceability.

Are addendums and amendments compatible with electronic signatures?

Yes, both addendums and amendments are fully compatible with electronic signatures under laws like the ESIGN Act and UETA, provided all parties sign the document in a way that clearly shows their intent to be bound by the new or revised terms.

What is the most common mistake people make when choosing between an addendum and an amendment?

The most common mistake people make is using an addendum to modify an existing clause, which creates ambiguity, because an addendum only adds content, so you should always use an amendment to change or strike out original language.

Can an addendum and an amendment be used interchangeably in a contract?

No, an addendum and an amendment cannot be used interchangeably because they serve distinct legal functions, so using the wrong one can invalidate the intended change, and you should always match the document type to whether you are adding or altering terms.

Can I switch from an addendum to an amendment after signing the original contract?

Yes, you can switch from an addendum to an amendment after signing the original contract, as long as all parties agree in writing and sign the new document, but you must ensure the switch clearly states that it supersedes the prior addendum to avoid confusion.

Difference Between

Difference Between Addendum and Amendment

Written byNex Virox Team

Editorial Team

Reviewed byVarshal Nirbhavane

Senior SEO & Organic Growth Professional · 5+ years

Published: September 2, 202621 min read

Quick answer

The main difference between Addendum and Amendment is that an addendum adds new information or terms to an existing contract without altering the original text, while an amendment changes, modifies, or revises specific provisions already contained within the original agreement. Addendum is supplementary material attached after execution, whereas Amendment is a formal revision that updates or corrects existing clauses.

Key takeaways

Core distinction: An addendum adds new information to an existing contract, while an amendment changes or modifies terms already present in the original agreement.
How each works: An addendum supplements the original contract without altering its existing clauses, whereas an amendment revises, deletes, or replaces specific provisions within the original document.
Cost and effort: Amendments typically require renegotiation and re-signing by all parties, making them more time-intensive; addendums are usually simpler, faster, and less costly to execute.
Best-fit use case: Use an addendum for adding a new scope of work or extra terms post-signing; use an amendment for correcting errors, changing payment terms, or extending a contract’s duration.
Common decision mistake: Parties often confuse the two, but choosing the wrong one can invalidate the original agreement, so always verify whether you are adding new content versus altering existing clauses.

Table of Contents18 sections

Difference Between Addendum and Amendment: Comparison Table

Aspect	Addendum	Amendment
Definition	Adds new terms or information to an existing contract without altering the original text.	Modifies, corrects, or changes specific terms already written in the original contract.
Purpose	Supplements the agreement with additional details, clarifications, or newly agreed-upon provisions.	Revises existing clauses to reflect changed circumstances, corrections, or new mutual agreements.
Core Mechanism	Attaches as a separate document that becomes part of the original contract upon signature.	Rewrites or replaces the language of specific clauses directly within the original contract document.
Original Text	Leaves every original clause fully intact and untouched in its existing form.	Alters, deletes, or supersedes the original wording of the targeted clause or section.
Document Structure	Exists as an independent, standalone page appended after the final signature block.	Appears as a revised section within the body, often with tracked changes or redlined text.
Typical Length	Often one to three pages, depending on the number of new terms being added.	Usually a few sentences to one page, focused narrowly on the clause being changed.
Common Use Case	Adds a new deliverable, additional scope of work, or extra compensation terms to a service agreement.	Changes a payment due date, adjusts a delivery schedule, or corrects a pricing error in a lease.
Execution Speed	Requires only the new page to be signed, making execution faster than redrafting the full contract.	Requires re-signing the revised clause or the entire document, which can take longer to process.
Legal Effect	Creates new binding obligations that run alongside, but do not replace, the original terms.	Supersedes and invalidates the prior version of the specific clause it modifies.
Reference Style	States it is attached to and incorporated by reference into the original agreement.	Explicitly names the section or paragraph number it replaces within the original document.
Number of Versions	Multiple addenda can stack sequentially, each adding new layers without changing prior ones.	Each amendment supersedes the last, so only the most recent version of a clause is active.
Contract Clarity	Keeps original text clean but requires readers to cross-check multiple attached pages.	Centralizes all changes in one place but can make the original document harder to read.
Audit Trail	Provides a clear chronological record of what was added and when it was attached.	Requires version control to track which amendment replaced which original clause over time.
Signature Requirement	Needs signatures from all original parties to the contract to be legally enforceable.	Needs signatures from all parties, and sometimes witnesses or notarization depending on contract type.
Notarization Need	Often skips notarization unless the original contract itself required it for validity.	May require notarization if the amendment touches real estate, wills, or other notarized instruments.
Real Estate Use	Adds a new parking space or storage unit right to an existing property purchase agreement.	Changes the closing date or purchase price after the original real estate contract was signed.
Construction Use	Adds a new work item, like extra lighting fixtures, to a fixed-price construction contract.	Changes the project completion deadline or alters the payment milestone schedule in the contract.
Employment Use	Adds a non-compete clause or a new bonus structure to an existing employment agreement.	Changes the base salary amount or modifies the job title and reporting line in the contract.
Lease Use	Adds a pet policy or a new parking rule to an existing residential lease agreement.	Changes the monthly rent amount or extends the lease term by six additional months.
Financial Impact	Introduces entirely new payment obligations or compensation amounts not in the original deal.	Adjusts existing payment figures, interest rates, or fee schedules already written in the contract.
Risk Profile	Adds new obligations that may introduce unforeseen risks if the new terms are not reviewed carefully.	Alters existing risk allocations, potentially shifting liability from one party to the other.
Dispute Resolution	New terms fall under the original contract's existing dispute resolution and governing law clauses.	Can change the arbitration venue or governing law if the amendment explicitly rewrites that clause.
Regulatory Compliance	New provisions must comply with regulations that were in effect at the time of the addendum's signing.	Revised clauses must meet current regulatory standards, which may have changed since the original signing.
Third-Party Impact	Adds new rights or obligations that may require consent from guarantors or insurers.	Changes existing obligations that could affect lenders, sureties, or other third-party stakeholders.
Contract Termination	Adds a new early-termination option or exit fee clause without touching the original termination section.	Rewrites the termination notice period or changes the penalties for early exit in the original clause.
Intellectual Property	Adds a new license grant or usage right for software or content not covered originally.	Changes the ownership assignment or modifies the royalty percentage in an existing IP clause.
Data Privacy	Adds a new data-processing schedule or a GDPR-specific annex to a master services agreement.	Revises the data retention period or changes the breach-notification timeline in the privacy clause.
Typical Users	Used by project managers and sales teams when scoping expands after the initial deal closes.	Used by legal counsel and contract administrators when terms need correction or renegotiation.
Primary Limitation	Cannot fix an error or change an existing term; it only adds new material on top.	Cannot add entirely new subject matter; it only revises what is already written in the contract.
Best-Fit Scenario	Best when the original deal stands but needs extra scope, deliverables, or new conditions attached.	Best when a specific clause is wrong, outdated, or no longer reflects the parties' current intent.

What Is Addendum?

An addendum is a document added to an existing contract to include new terms, clarify details, or update information without rewriting the entire agreement. It becomes part of the original contract once both parties sign it. Addendums are commonly used in real estate, employment, and publishing deals.

Definition of Addendum

An addendum is a supplementary legal document attached to an original contract that adds, explains, or modifies specific provisions while leaving the rest of the agreement intact. It requires the same signatures as the primary contract to be legally binding. Addendums do not replace the original document; they extend it.

Key Characteristics of Addendum

Characteristic	What It Means in Practice
Supplementary nature	It attaches to the main contract and never stands alone as a separate agreement.
Mutual consent required	All original parties must sign the addendum for it to take legal effect.
Preserves original terms	Existing clauses remain unchanged unless the addendum explicitly overrides them.
Specific scope	It addresses only the new or clarified items, not the entire contract.
Binding legal force	Once signed, it carries the same enforceability as the original contract.
Reference to original	It must cite the original contract date and parties to avoid ambiguity.
No expiration default	It remains effective until the underlying contract ends or is replaced.
Sequential numbering	Multiple addendums are numbered (e.g., Addendum 1, 2) to track changes.
Distinct from amendment	An addendum adds new terms; an amendment changes existing terms.
Common in transactions	It handles late discoveries like new fixtures, payment plans, or scope additions.

Common Examples of Addendum

Real estate purchase addendum – Adds contingencies like home inspection or financing deadlines to a property sale contract.
Employment contract addendum – Adds a non-compete clause or remote work policy after the initial job offer.
Lease agreement addendum – Adds pet permission or parking rules to a residential rental lease.
Publishing book addendum – Adds ebook rights or audio rights to a print-only author contract.
Construction project addendum – Adds new building materials or design changes to a fixed-bid construction contract.
Loan agreement addendum – Adds a co-signer or changes the repayment schedule on a personal loan.
Software license addendum – Adds data processing terms or user limits to a standard software license.
Event venue addendum – Adds a rain date or security staffing requirement to an event rental agreement.
Vendor supply addendum – Adds a quality control standard or delivery frequency to a supplier contract.
Divorce settlement addendum – Adds a college tuition payment plan to an existing child support agreement.

Advantages and Limitations of Addendum

Advantages	Limitations
Fast to execute compared to drafting a new contract from scratch.	Cannot fix a fundamentally flawed original contract without a full rewrite.
Cost-effective because it requires minimal legal drafting time.	Poorly worded addendums can create conflicts with original clauses.
Preserves the original contract's negotiated terms and history.	Requires fresh signatures from every party, which can delay urgent changes.
Provides clear documentation of every change made over time.	Multiple addendums can make the contract confusing and hard to read.
Flexible for adding terms discovered after the original signing.	Not valid if it contradicts a mandatory legal requirement in the original contract.
Reduces risk of misinterpretation by keeping changes in one place.	Unnotarized addendums may be rejected for certain real estate filings.
Allows incremental updates without renegotiating the whole deal.	No legal effect if it fails to reference the original contract accurately.
Useful for both minor tweaks and substantial additions like new parties.	Cannot alter the contract's effective date retroactively without explicit language.
Widely accepted across industries including real estate, law, and tech.	May require separate witness signatures in some jurisdictions to be enforceable.
Helps maintain a clean audit trail for compliance or dispute resolution.	Often overlooked by parties who assume verbal agreements are enough.

What Is Amendment?

Amendment is a formal change, correction, or addition made to an existing legal document, contract, law, or regulation. It modifies the original terms to reflect new agreements, correct errors, or update provisions. An amendment exists to keep documents accurate, current, and legally enforceable without requiring a complete rewrite.

Definition of Amendment

An amendment is a formal, documented alteration to an existing legal instrument that adds, removes, or revises specific provisions while leaving the remainder of the original document intact and in force. It requires mutual consent from all bound parties or, in legislation, proper parliamentary procedure to become legally valid.

Key Characteristics of Amendment

Characteristic	What It Means in Practice
Modifies existing text	Changes specific clauses or sections without replacing the whole document.
Requires mutual consent	All signing parties must agree to the change for it to bind anyone.
Preserves original document	The base agreement stays intact; only targeted parts are altered.
Creates a permanent record	Leaves a dated, written trail of what changed and when.
Needs formal execution	Must be signed, dated, and often witnessed like the original contract.
References specific clauses	Names the exact section or term being changed to avoid ambiguity.
Can be temporary or permanent	Some amendments expire on a date; others last for the document's life.
Carries equal legal weight	Once signed, the amendment is as enforceable as the original terms.
Requires clear drafting	Vague language creates disputes, so precise wording is mandatory.
Supersedes conflicting terms	Where the amendment and original clash, the amendment wins.

Common Examples of Amendment

U.S. Constitution First Amendment – guarantees freedoms of speech, religion, press, assembly, and petition.
Employment contract salary change – updates compensation terms after a promotion or raise.
Lease agreement pet clause – adds permission for a tenant to keep an animal.
Tax code revision – alters deduction rules or income brackets in federal law.
Real estate purchase addendum – changes the closing date or inspection contingency.
Corporate bylaws change – adjusts voting thresholds or board meeting requirements.
Insurance policy rider – adds coverage for specific valuables like jewellery or art.
NDA scope expansion – broadens confidential information to include verbal disclosures.
Civil Rights Act amendment – extends protections to new classes or enforcement powers.
Service agreement pricing update – adjusts monthly fees or adds late-payment penalties.

Advantages and Limitations of Amendment

Advantages	Limitations
Fast to execute compared to drafting an entirely new contract.	Requires unanimous consent, so one holdout can block the change.
Preserves the original agreement's terms that still work well.	Multiple amendments over time create a patchwork that is hard to read.
Provides a clear audit trail of every change and its date.	Poorly drafted wording can create contradictions with the original text.
Cheaper than legal redrafting of the full document.	Cannot fix fundamental flaws in the original contract's structure.
Allows incremental updates as circumstances evolve.	Each amendment carries negotiation risk that can stall other business.
Keeps the core relationship and terms stable while adjusting details.	If not properly signed, an amendment can be challenged as unenforceable.
Useful for correcting genuine errors like typos or wrong dates.	Over-amendment can make the original document legally confusing.
Does not trigger renegotiation of unrelated clauses.	State or federal law may impose formalities that are easy to miss.
Provides flexibility without terminating the existing agreement.	Oral amendments are often unenforceable; written form is mandatory.
Can be tailored narrowly to solve one specific problem.	Creates a risk of unintended consequences in linked clauses.

Similarities Between Addendum and Amendment

Shared Aspect	How Addendum and Amendment Are Alike
Contractual Purpose	Both addendum and amendment formally modify the terms of an existing, valid contract between parties.
Legal Category	Both addendum and amendment are recognized legal instruments used to alter a binding agreement's original text.
Written Format	Both addendum and amendment are typically documented in writing to create a clear, enforceable record.
Signature Requirement	Both addendum and amendment usually require signatures from all original parties to become legally effective.
Binding Effect	Both addendum and amendment create legally enforceable obligations once properly executed by the involved parties.
Reference Document	Both addendum and amendment must reference the original contract by name or date for validity.
Integration Clause	Both addendum and amendment are typically incorporated into the master agreement through an integration clause.
Consent Requirement	Both addendum and amendment require mutual consent from every party bound by the original contract.
Change Mechanism	Both addendum and amendment serve as the primary mechanism for changing a contract after initial signing.
Legal Standards	Both addendum and amendment must comply with the same contract law standards governing the original document.
Consideration Basis	Both addendum and amendment often require new consideration to support the modification of the agreement.
Dispute Resolution	Both addendum and amendment are subject to the original contract's arbitration or litigation clauses.
Statute of Frauds	Both addendum and amendment must satisfy the statute of frauds if the original contract required writing.
Record Keeping	Both addendum and amendment should be stored with the original contract for future reference and audit.
Party Identification	Both addendum and amendment name the same parties as the original contract to maintain legal continuity.
Execution Date	Both addendum and amendment include an execution date that records when the modification becomes effective.
Legal Counsel	Both addendum and amendment are typically reviewed by attorneys to ensure compliance and enforceability.
Breach Consequences	Both addendum and amendment carry the same breach remedies as the original contract terms.
Governing Law	Both addendum and amendment remain subject to the governing law specified in the original agreement.
Negotiation Process	Both addendum and amendment require negotiation between parties before final terms are accepted.
Documentation Role	Both addendum and amendment serve as official supplementary documentation to the master contract file.
Termination Clause	Both addendum and amendment can be superseded or terminated by a later modification document.
Counterpart Execution	Both addendum and amendment may be signed in counterparts by parties in different locations.
Electronic Signatures	Both addendum and amendment can be executed using valid electronic signature platforms like DocuSign.
Audit Trail	Both addendum and amendment create a clear audit trail showing the contract's evolution over time.
Ambiguity Risk	Both addendum and amendment risk ambiguity if drafted with vague or conflicting language.
Interpretation Rules	Both addendum and amendment are interpreted using the same rules of contract construction as the original.
Third-Party Rights	Both addendum and amendment can affect third-party beneficiaries named in the original contract.
Maintenance Duty	Both addendum and amendment require ongoing review to ensure they remain consistent with current operations.
Long-Term Record	Both addendum and amendment remain part of the permanent legal record after the contract concludes.

Addendum or Amendment: Which Should You Choose?

The single deciding variable is timing relative to signing. Choose Addendum for changes made before both parties sign the original contract. Choose Amendment for changes made after the contract is already legally binding and executed.

When to Use Addendum

Choose Addendum when the original contract is unsigned or still in negotiation. Use it to add new terms, attach extra specifications, or correct a missing detail without altering existing clauses. It suits pre-signing revisions, project scope additions, and last-minute pricing adjustments.

When to Use Amendment

Choose Amendment when the contract is already signed and legally enforceable. Use it to modify, delete, or replace existing terms such as payment schedules, deadlines, or renewal conditions. It suits post-signing renegotiations, extended timelines, and changed regulatory requirements.

Common Misconceptions About Addendum and Amendment

Common Myth	The Reality
An addendum and an amendment are the exact same legal document.	An addendum adds new terms to an existing contract, while an amendment changes or modifies terms already written in the original agreement.
You can use either term interchangeably in any legal context.	Legal professionals use addendum for additions and amendment for modifications, and using the wrong term can create confusion about the document's purpose.
An addendum always replaces the original contract entirely.	An addendum supplements the original contract by adding new provisions, but the original contract remains fully intact and enforceable alongside the addendum.
An amendment is only used for real estate purchase agreements.	An amendment applies to any contract type, including employment agreements, leases, service contracts, and sales agreements, not just real estate transactions.
An addendum requires both parties to sign a completely new contract.	An addendum is a separate document attached to the original contract, and both parties sign only the addendum page, not a rewritten version of the full agreement.
An amendment must be notarized to be legally valid.	An amendment is valid when both parties sign it, and notarization is only required if the original contract specifically demands notarized modifications.
An addendum can change the price stated in the original contract.	An addendum adds new terms but cannot alter existing price terms; changing a price requires an amendment that explicitly modifies the original clause.
An amendment is always written after the contract is fully executed.	An amendment can occur before or after execution, but it always modifies terms that already exist in the signed agreement between the parties.
An addendum is only used for real estate transactions.	An addendum is common in real estate, but it also appears in employment contracts, construction agreements, and purchase orders across many industries.
An amendment completely voids the original contract document.	An amendment modifies specific clauses while the rest of the original contract remains valid, and only the amended terms are replaced by the new language.
An addendum must be attached to the contract before signing.	An addendum can be added after the original signing, and parties often execute addenda later to address new requirements or additional scope of work.
An amendment changes the subject matter of the entire agreement.	An amendment changes only the specific clause it addresses, such as delivery dates or payment terms, while the contract's core subject matter stays unchanged.
An addendum and an amendment have the same legal weight in court.	Both carry legal weight, but an amendment directly alters original terms, whereas an addendum adds new terms that do not conflict with existing provisions.
An addendum is always shorter than an amendment document.	Length depends on content, not document type; an addendum can be lengthy if it adds many new provisions, and an amendment can be a single sentence.
An amendment requires approval from a third party like a judge.	An amendment requires only mutual consent from the contracting parties, and court approval is unnecessary unless the contract is part of litigation or a court order.
An addendum is only valid if it is signed on the same day as the original.	An addendum is valid whenever both parties sign it, regardless of the date, provided the original contract is still active and the parties agree to the addition.
An amendment can be verbal and does not need to be written down.	An amendment should be written and signed to be enforceable, especially when the original contract contains a clause requiring modifications to be in writing.
An addendum automatically cancels the original contract's terms.	An addendum adds terms without canceling original provisions, and any conflict between the addendum and the original contract is typically resolved in favor of the addendum.
An amendment is used only to fix mistakes in a contract.	An amendment is used for any change, including updating prices, extending deadlines, or altering responsibilities, not just correcting errors or typos in the original text.
An addendum is the same as a rider in insurance policies.	A rider is a type of addendum specific to insurance, but an addendum is a broader term used across all contract types, including leases and service agreements.
An amendment must be signed by every party involved in the original deal.	An amendment must be signed by all parties who are bound by the change, which is typically the same signatories as the original contract, but not necessarily every minor participant.
An addendum cannot be used to extend a contract's expiration date.	An addendum can add a new extension clause, but changing an existing expiration date requires an amendment because that date is already a term in the original contract.
An amendment is only valid during the contract's initial term.	An amendment can be executed during the contract term or even after expiration if the parties agree to revive or modify obligations, depending on applicable law.
An addendum is always created by the seller or service provider.	Either party can draft an addendum, and the buyer or client often proposes additions to address their specific needs or concerns before the deal closes.
An amendment changes the title or heading of the original contract.	An amendment changes the body text of specific clauses, but the contract's title and heading remain the same unless the parties explicitly agree to rename the entire document.
An addendum is only used when the contract is incomplete.	An addendum is also used to add new terms after completion, such as additional deliverables or updated contact information, even when the original contract is fully formed.
An amendment must be filed with a government agency to take effect.	An amendment takes effect upon mutual signature, and government filing is only required for specific regulated contracts like corporate bylaws or land records.
An addendum cannot be referenced in the original contract's table of contents.	An addendum is often listed as an attachment in the original contract's table of contents, but it can also be added later without updating the original index.
An amendment is the same as a contract novation.	An amendment changes terms within an existing contract, while a novation replaces one party with a new party, which is a fundamentally different legal action.
An addendum is only valid if it is stapled to the original contract.	An addendum is valid if it is incorporated by reference in the original contract or signed separately, and physical attachment is not a legal requirement for enforceability.

Conclusion

Difference Between Addendum and Amendment comes down to timing and purpose. An addendum adds new terms to an existing contract without altering original text. An amendment changes or modifies existing provisions. Choose an addendum for additional details; choose an amendment for revising current terms. Both require mutual consent to remain legally valid.

FAQs on Difference Between Addendum and Amendment

What is the legal definition of an addendum?: An addendum is a document that adds new terms or information to an existing contract without altering the original text, making it a practical tool for including supplementary details like additional deliverables or updated schedules after the initial agreement has been signed.
What is the legal definition of an amendment?: An amendment is a formal change that modifies, deletes, or replaces specific provisions within an existing contract, requiring the same level of consent as the original agreement and resulting in a revised version of the original terms rather than a separate addition.
What is the main difference between an addendum and an amendment?: The main difference is that an addendum adds new terms without changing existing ones, while an amendment alters or replaces current provisions, so an addendum expands the contract's scope and an amendment revises its core content.
Which is better for a real estate purchase agreement: an addendum or an amendment?: An addendum is better for a real estate purchase agreement when you need to add new conditions like a home inspection contingency or seller credits, whereas an amendment is better when you must change the purchase price, closing date, or property description already written in the contract.
Does an addendum cost more than an amendment to prepare?: An addendum typically costs the same as an amendment, often ranging from $150 to $500 for attorney preparation, but the price depends on complexity and location rather than the document type, so you should budget based on the specific changes needed.
Is it safe to use an addendum instead of an amendment for a contract change?: It is safe to use an addendum instead of an amendment only if you are adding new terms, but it is risky if you intend to change existing terms, as using the wrong document can create conflicting provisions and lead to legal disputes over enforceability.
Are addendums and amendments compatible with electronic signatures?: Yes, both addendums and amendments are fully compatible with electronic signatures under laws like the ESIGN Act and UETA, provided all parties sign the document in a way that clearly shows their intent to be bound by the new or revised terms.
What is the most common mistake people make when choosing between an addendum and an amendment?: The most common mistake people make is using an addendum to modify an existing clause, which creates ambiguity, because an addendum only adds content, so you should always use an amendment to change or strike out original language.
Can an addendum and an amendment be used interchangeably in a contract?: No, an addendum and an amendment cannot be used interchangeably because they serve distinct legal functions, so using the wrong one can invalidate the intended change, and you should always match the document type to whether you are adding or altering terms.
Can I switch from an addendum to an amendment after signing the original contract?: Yes, you can switch from an addendum to an amendment after signing the original contract, as long as all parties agree in writing and sign the new document, but you must ensure the switch clearly states that it supersedes the prior addendum to avoid confusion.