Contract Addendums in Indonesia: When to Use One, What It Contains and How to Track the Version in Force

Few contracts run to the end without a change, and a new price, a longer term or a new deadline usually goes into an addendum. This guide explains when an addendum is enough, what it should contain under Indonesian law and practice, and how to keep track of which terms are currently in force.

Note: This guide is general information and not legal advice. If the original agreement is a notarial deed, involves a foreign party, is a government procurement contract or carries a large value, talk to your legal adviser.

What a contract addendum is

Neither "addendum" nor "amendment" is a statutory term in the Indonesian Civil Code (KUHPerdata), which deals only with agreements and their binding force. Both are practice terms. The official Indonesian dictionary defines an addendum as an additional provision or article, and in practice it forms one unit with the main agreement.

An addendum usually adds terms while an amendment changes existing ones, but the two words are used interchangeably because both are a new agreement between the same parties that modifies the old one. This guide uses "addendum" for both.

When to use an addendum and when to sign a new contract

An addendum fits when the change still relates to the subject of the existing agreement. Typical examples are a new contract value, a longer term, extra work of the same kind or a new reporting deadline. For new content that has nothing to do with the main agreement, such as a completely different service, the Indonesian legal publication Hukumonline advises a new agreement instead. An addendum may also be signed before the original term ends, as long as the parties agree.

The legal basis for changing a contract

Article 1338(1) of the Civil Code says that an agreement made in accordance with the law binds the parties who made it as if it were law. Article 1338(2) adds that an agreement cannot be revoked except by agreement of both parties or for reasons set by law. Article 1338(3) requires agreements to be performed in good faith.

As a result, one party cannot change a contract on its own, so a one-sided email announcing a price increase does not amend it. Every party has to agree, and if they can't, Hukumonline says the change or cancellation should go to a judge.

An addendum is itself an agreement, so it has to meet the four validity conditions in Article 1320 of the Civil Code. They are consent, capacity, a definite subject matter and a lawful cause. Different changes may take effect on different dates if the parties agree and the arrangement is lawful, provided each date is stated explicitly.

Government procurement contracts have their own rules on contract changes, and this guide does not cover them.

The addendum follows the form of the original

No article of the Civil Code says that an addendum must take the same form as the original agreement. The rule comes from practice, and a notary writing in Hukumonline put it as the principle that you change something with the same type of instrument. In practice it works like this.

• Private (underhand) agreement: the addendum is also a private document signed by all parties. Small typos can be fixed by renvoi, which means striking the error, correcting it in the margin and initialling the correction.
• Agreement legalised by a notary: make the change before the same notary.
• Notarial deed, or a contract type whose form is set by law: make the amendment in the same form. This is the safest reading, although no article states it outright.

If your contract has its own amendment clause, such as a rule that changes are valid only in writing and signed by the parties, follow it.

Signing an addendum electronically

An addendum can be an electronic contract, and it is valid on the same four conditions as any other agreement (Government Regulation 71 of 2019, Article 46(2)). An electronic contract addressed to Indonesian residents must also be in Bahasa Indonesia. An electronic signature is valid as long as it meets Article 11 of the Electronic Information and Transactions Law (UU ITE), and a certified electronic signature is easier to prove. See the guide to electronic and digital signatures and the guide to signing a PDF. If the original was signed in ink, the suggested practice is to add a clause in which the parties agree to sign electronically. The clause should also treat electronic signatures as equal to handwritten ones.

If the original is a notarial deed, or a law requires a specific form, don't assume an electronic addendum is enough. Since its 2024 amendment, UU ITE still gives way where another law provides otherwise, and whether notarial deeds can be fully electronic remains unresolved.

Who may sign for a company

For a limited liability company (PT), Article 98(1) of Law 40 of 2007 says the board of directors represents the company in and out of court. When there is more than one director, each may represent the company unless the articles of association say otherwise. That authority can also be limited by law, the articles of association or a resolution of the general meeting of shareholders. A director may not represent the company in a dispute with it or when there is a conflict of interest.

The board may give employees or others a written power of attorney for specific legal acts described in that power of attorney (Article 103). According to Hukumonline, authority given only orally is not valid.

The articles of association may also require written approval from the board of commissioners for certain acts (Article 117). If that approval is missing, the act still binds the company when the other party acted in good faith, but the requirement in the articles still has to be met.

In practice, whoever signs the addendum should have the same authority as the original signatory, or a valid new one. Check the articles of association and any power of attorney before signing, especially if that official has changed.

The language of the addendum

Part of the rule is settled. Article 31(1) of Law 24 of 2009 requires Bahasa Indonesia in agreements that involve an Indonesian private institution or an Indonesian citizen. When a foreign party is involved, Article 31(2) says the agreement is also written in that party's national language and/or English. Article 26 of Presidential Regulation 63 of 2019 adds that the foreign-language text is an equivalent or translation of the Indonesian text. If the versions are read differently, the language the parties chose in the agreement governs.

What is still contested is the consequence of breaching this requirement. The Language Law states no sanction. According to commentary in Hukumonline, courts in several cases have declared an English-only agreement void because it lacked a lawful cause. One of those cases ended with Supreme Court decision No. 1572 K/Pdt/2015. On the other side, an opinion piece there quotes Supreme Court Circular (SEMA) 3 of 2023: a missing Indonesian version cannot be a reason to cancel a contract with a foreign party. The exception is when bad faith is proven. A SEMA is guidance and some legal scholars criticise this one, so the outcome of a dispute cannot be guaranteed.

Because an addendum is itself an agreement, treat Article 31 as applying to it. The risk is easy to manage:

• write the addendum in Bahasa Indonesia;
• if the original is bilingual, make the addendum bilingual as well;
• repeat the governing-language clause from the original, or state expressly that it applies to the addendum.

What an addendum should contain

Number addendums in sequence (Addendum I, II, III) and never reuse a number.

Sample addendum structure

This outline only shows the usual order of contents, and it does not replace a template from your legal adviser.

1. Title: Addendum II to Cooperation Agreement No. PKS-014/2026 dated 2 January 2026.
2. Parties: company details, the name and position of each signatory, and the basis of their authority (articles of association or power of attorney).
3. Recitals: the title, number, date and parties of the main agreement, a reference to Addendum I, and the reason for the change.
4. Article 1, Amendments: each changed clause with its old wording and its new wording.
5. Article 2, Additional provisions: any new article and its number.
6. Article 3, Effective date: one date for all changes, or a date per clause.
7. Article 4, Other provisions: clauses not changed remain fully in force, and the addendum forms one unit with the main agreement.
8. Article 5, Language: the language versions and which one governs if they are read differently.
9. Closing: place and date of signing and the number of counterparts.
10. Signatures of the parties and the e-Meterai.

For Article 1, quote the old and new wording in full. For example: "Article 7(2) originally read 'the report shall be delivered within five (5) business days after the end of each month'. It is amended to read 'the report shall be delivered within three (3) business days after the end of each month'."

e-Meterai on an addendum

An addendum is an agreement, so it is an object of Indonesian stamp duty whatever its value. The Rp5,000,000 threshold applies only to receipt-type documents and never to agreements. The duty is Rp10,000 per document, and each counterpart counts as a separate document. For agreements, the duty arises when the document is signed, including when it is signed electronically.

The Stamp Duty Law does not mention addendums specifically. Because an addendum is signed as a separate document, the safe practice is to treat each one as its own object of stamp duty. Don't rely on the stamp on the main agreement to cover it. The guide to e-Meterai for company documents explains how to apply it and who pays.

Tracking the version in force with an amendment register

After two or three addendums, people start asking which wording of a clause applies today. The answer belongs in an amendment register kept with the main agreement, like this one.

Fill in the register on the day each addendum is signed, store the signed file with the main agreement, and use one file-naming pattern for every addendum. If your team prepares a consolidated text for internal reading, label it as a reading aid, because the main agreement and the signed addendums remain the binding documents.

Common mistakes

• Changing a contract by email or in meeting minutes without the agreement of every party.
• Writing "Article 7 is amended" without the old and new wording, or without a full reference to the main agreement.
• Leaving out the effective date and the statement that other clauses remain in force.
• Having the addendum signed by someone without authority under the articles of association or a power of attorney.
• Drafting the addendum only in English when an Indonesian party is involved.
• Assuming the stamp on the main agreement also covers the addendum.
• Amending a notarial deed with a private addendum without consulting the notary.

How Obscura helps

In Obscura, an amendment that changes part of an agreement is recorded beside that agreement on the project's relationship graph. When a new version of the agreement becomes current, Contract Intelligence opens a review task to check the terms, parties and obligations again. The record shows who finished the review and when. If an amendment changes a term that was already reviewed, Obscura shows the previously reviewed term beside the suggested replacement, and the earlier period stays on record. Once an obligation is confirmed, you choose who is responsible for it and how many days ahead Obscura should remind them. Extracting terms with AI also needs the AI module, and the Contract Intelligence page has the details.

With document control, every upload becomes a new version while earlier versions stay available to view. Reviewers can compare two versions before they approve a revision, and the audit log records the changes, decisions and activity on each document.