Which Contract Controls When the Purchase Order, Quotation, and Main Agreement Conflict?

Short Answer

When a purchase order, quotation, and main agreement contain conflicting terms, the controlling document depends on the contract structure, the parties’ conduct, and the applicable law.

In Korea, the answer is not simply that the latest document controls or that a purchase order automatically changes the main agreement. The key questions are whether the contract contains an order of precedence clause, whether the later document was clearly agreed to as an amendment, and whether any standard terms were properly incorporated into the contract.

In practice, disputes often arise when a main agreement, purchase order, quotation, invoice, technical specification, or standard terms and conditions contain different provisions on price, delivery, inspection, warranty, liability, governing law, jurisdiction, or remedies.

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Why Do These Conflicts Matter?

Document conflicts can determine the outcome of a commercial dispute.

For example, the main agreement may contain a liability cap, while the purchase order is silent. A quotation may include the supplier’s standard terms, while the buyer’s purchase order contains different inspection and warranty terms. An invoice may refer to late payment interest, collection costs, or jurisdiction terms that were not included in the signed agreement.

When a dispute arises, each party may rely on the document most favorable to its position.

The dispute may therefore begin not with the question of who breached the contract, but with the more basic question of which document forms part of the contract and which term controls.

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Key Issues When Contract Documents Conflict

Issue 1: Does the Contract Have an Order of Precedence Clause?

A well-drafted main agreement should state the order in which contract documents prevail if they conflict.

For example, the contract may provide that the following order applies:

1. Signed amendments
2. The main agreement
3. Statements of work or specifications
4. Purchase orders
5. Quotations
6. Standard terms and conditions

This type of order of precedence clause can significantly reduce uncertainty.

Without it, the parties may have to rely on contract interpretation, negotiation history, course of performance, trade practice, and evidence of actual agreement.

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Issue 2: Did a Later Document Actually Amend the Main Agreement?

Foreign companies should be careful about assuming that a later purchase order, quotation, email, or invoice automatically changes the original contract.

Under Korean contract principles, a contract generally cannot be changed unless there is a clear agreement to amend it, whether express or implied.

A later document may be relevant evidence, but it does not automatically override the main agreement merely because it was sent later or because the other party did not immediately object.

This is especially important where the later document attempts to change important terms such as price, liability, payment deadline, warranty, governing law, jurisdiction, or dispute resolution.

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Issue 3: Are Standard Terms Properly Incorporated?

Many disputes involve standard terms attached to or referenced in a quotation, purchase order, invoice, or website.

For example:

• The seller’s quotation may refer to the seller’s standard sales terms.
• The buyer’s purchase order may include the buyer’s purchase terms.
• An invoice may include payment, interest, or jurisdiction provisions.
• A delivery note may refer to warranty or claim procedures.

If those standard terms were not clearly incorporated into the contract, they may be difficult to rely on later.

Where standard terms are treated as terms and conditions, Korean law may also consider issues such as incorporation, interpretation, individual agreement, and fairness control.

As a practical matter, individually negotiated terms are generally stronger than conflicting boilerplate standard terms.

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Common Conflict Scenarios

Main Agreement vs. Purchase Order

A main agreement often governs the overall relationship, while purchase orders govern individual transactions such as quantity, delivery date, product model, and price.

However, problems arise when a purchase order attempts to change broader legal terms, such as liability, warranty, governing law, jurisdiction, indemnity, or termination rights.

If the main agreement says that purchase orders cannot modify the agreement unless expressly signed by authorized representatives, the purchase order will usually be harder to rely on as an amendment.

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Quotation vs. Purchase Order

A quotation and purchase order often contain different terms because each party uses its own form.

The supplier may send a quotation with its own standard conditions. The buyer may then issue a purchase order with different standard conditions. Performance may begin without anyone resolving the conflict.

In that situation, the key question is usually not just which document came first or last, but which terms the parties actually agreed to and how they performed the transaction.

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Standard Terms vs. Individually Negotiated Terms

If a signed agreement or special condition directly conflicts with standard terms, the individually agreed term is usually more likely to control.

This is why parties should not rely only on standard terms printed on the back of a purchase order, attached to a quotation, or referenced in small print on an invoice.

Important legal terms should be included clearly in the signed contract or expressly incorporated by reference.

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Why “No Objection” May Not Be Enough

A common assumption is that if one party sends a document and the other party does not object, the document becomes binding.

That assumption can be risky.

Silence may be relevant in some circumstances, especially where the parties have an established course of dealing. However, for important changes, it is usually safer to obtain a clear written agreement.

For example, if a purchase order changes the payment deadline, liability cap, governing law, or dispute forum, the party relying on that change may face difficulty if there is no clear evidence that the other party agreed to it.

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What If the CISG Applies?

In international sale of goods transactions, the CISG may apply if the relevant requirements are satisfied.

If the CISG applies, the parties’ statements and conduct may be interpreted based on their intent, the other party’s understanding, the surrounding circumstances, negotiation history, practices between the parties, trade usages, and subsequent conduct.

This means that in cross-border sales disputes, evidence of negotiations, repeated practice, purchase order history, shipment records, invoice treatment, inspection records, and later communications can become important.

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Practical Drafting Tips

Foreign companies should consider the following steps before signing or performing a contract with a Korean counterparty:

• Include a clear order of precedence clause.
• State whether purchase orders are limited to quantity, price, delivery, and product details.
• Provide that any amendment must be made in a signed writing by authorized representatives.
• Clearly incorporate or exclude standard terms and conditions.
• Avoid relying on invoice terms or quotation footnotes for important legal provisions.
• Keep consistent records of which documents were accepted and performed.
• Ensure that technical specifications and drawing revisions are properly identified.
• Confirm whether the contract excludes or allows modification by email or course of dealing.

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Conclusion

When a purchase order, quotation, and main agreement conflict, the answer is not automatic.

The controlling document depends on the contract language, document hierarchy, amendment provisions, standard terms, course of performance, and evidence of the parties’ actual agreement.

For foreign companies contracting with Korean businesses, the safest approach is to resolve document hierarchy and amendment rules before performance begins. Otherwise, the parties may later spend significant time and cost arguing over which contract terms governed the deal in the first place.

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