A supplier usually cannot change the price after delivery is already completed if the buyer and supplier had already agreed on the price, the goods were delivered, and the buyer accepted them under that agreement. In Philippine law, a supplier cannot simply send a “revised invoice” or demand a higher amount after the fact just because costs increased, the supplier miscalculated, or market prices changed. The answer can change, however, if the contract itself allows price adjustment, the original price was not actually fixed, the buyer later agreed to the change, or the extra charge is for additional goods or services that were not part of the original order.

The basic rule: the agreed price binds both supplier and buyer

In the Philippines, supply transactions are usually governed by the Civil Code of the Philippines, especially the rules on obligations, contracts, and sales.

The starting point is simple: once there is a valid agreement, both sides must follow it in good faith. Article 1159 of the Civil Code says that obligations arising from contracts have the force of law between the parties.

For an ordinary supply transaction, a contract may be formed even without a long written contract. It can be formed through:

a signed supply agreement;
a purchase order accepted by the supplier;
an approved quotation;
an exchange of emails, Viber, Messenger, WhatsApp, or text messages;
a sales invoice plus delivery and acceptance;
repeated transactions showing a regular agreed price or pricing method.

Under Article 1305, a contract is a “meeting of minds” where one party binds himself to give something or render service to another. Under Article 1475, a sale is perfected when there is a meeting of minds on the thing sold and the price.

So if the buyer ordered 500 sacks of cement at ₱240 per sack, the supplier accepted, delivered the cement, and the buyer received it, the supplier generally cannot later say, “Actually, the price is now ₱270 per sack,” unless there is a legal or contractual basis for that adjustment.

Why a unilateral price increase is usually invalid

The most important Civil Code provision for this issue is Article 1308:

The contract must bind both contracting parties; its validity or compliance cannot be left to the will of one of them.

This is called the principle of mutuality of contracts. In plain English, one party cannot control the contract alone.

That means a supplier cannot reserve for itself an unlimited right to change the price after delivery without the buyer’s agreement. Even if the supplier’s costs went up, that business risk does not automatically transfer to the buyer.

A clause such as “supplier may adjust prices at any time” may also be questioned if it gives the supplier absolute discretion without a clear formula, standard, or agreed basis. Philippine law allows parties to agree on terms under Article 1306, but those terms must not violate law, morals, good customs, public order, or public policy.

When the price is considered final

The price is usually treated as final when the facts show that the parties already agreed on it and acted on that agreement.

Common examples:

Situation	Likely effect
Buyer issued a purchase order with a specific unit price and supplier delivered	Supplier is generally bound by that price
Supplier sent a quotation, buyer accepted, supplier delivered	Quoted price is usually enforceable
Sales invoice states the price and buyer paid or accepted delivery	Strong evidence of the agreed price
Delivery receipt states quantity only, but PO or quotation states price	PO or quotation helps prove the price
No written price, but parties used the same price in repeated past transactions	Past dealings may help prove the agreed price
Price was expressly “subject to final confirmation” and no final price was agreed	There may be a dispute on whether a final contract existed

Delivery matters because Article 1477 of the Civil Code provides that ownership of the thing sold is transferred to the buyer upon actual or constructive delivery, unless the parties agreed otherwise. Once delivery and acceptance happen under a fixed price arrangement, the supplier’s remedy is normally to collect the agreed price, not invent a new one.

Important exceptions: when a supplier may have a valid basis to adjust the price

There are situations where a supplier may legally demand more after delivery. The key question is whether the increase is truly authorized by the contract, law, or later agreement.

1. The contract has a valid price escalation clause

A price escalation clause is a contract term allowing price adjustment under specified conditions.

Examples:

“Price is subject to adjustment based on the DTI-published SRP as of delivery date.”
“Fuel surcharge applies if diesel prices exceed ₱X per liter.”
“Final price shall be based on prevailing supplier price list on date of delivery.”
“Imported goods are subject to foreign exchange adjustment based on BSP rate on billing date.”
“VAT, duties, customs charges, and government fees shall be for buyer’s account if imposed after quotation.”

For the clause to be safer and more enforceable, it should be:

written clearly;
agreed before delivery;
based on an objective formula or external reference;
not left entirely to the supplier’s whim;
applied consistently and in good faith.

A vague statement like “prices may change without notice” is weaker than a clear formula. If the supplier relies on such a clause, the buyer should ask: What exact contract provision allows this increase, and how was the new amount computed?

2. The original price was not fixed but was determinable

Philippine law does not always require a peso amount to be written immediately. Under Article 1469 of the Civil Code, the price may be considered certain if it can be determined with reference to another certain thing, or by a third person.

For example, the contract may say:

“Price shall be based on the published price of Brand X on delivery date.”
“Final price shall be the Manila market price on the date of release.”
“Price shall be determined by the agreed independent appraiser.”

But Article 1473 is important: the fixing of the price can never be left to the discretion of only one contracting party. If the supplier alone decides the final price, without a standard or buyer acceptance, the buyer can challenge it.

3. The buyer accepted the new price after delivery

A supplier’s revised invoice does not automatically change the contract. But the buyer’s later conduct may matter.

The supplier may argue that the buyer agreed to the new price if the buyer:

signed the revised invoice;
issued a new purchase order at the higher price;
paid the higher amount without protest;
sent an email approving the adjustment;
continued ordering under the revised pricing terms;
expressly acknowledged the corrected amount.

This is why buyers should be careful with words like “noted,” “approved,” “OK,” or “we will settle” in business chats. In a dispute, those messages may be used as evidence of acceptance.

If the buyer does not agree with the increase, the safer response is to object clearly and in writing.

4. The increase is not a price change but a correction of a genuine error

There is a difference between a price increase and a correction of a clerical or mathematical error.

For example:

the quotation says 100 units at ₱1,000 each, but the invoice total says ₱10,000 instead of ₱100,000;
the invoice accidentally omitted one delivered item;
VAT was mistakenly excluded despite the contract saying the price is VAT-exclusive;
the quantity billed does not match the quantity actually delivered and accepted.

If the supplier can prove an obvious error, the buyer may not be allowed to take unfair advantage of it. Article 22 of the Civil Code states that every person who acquires or comes into possession of something at the expense of another without just or legal ground must return it.

Still, the supplier must prove the error. A sudden “cost adjustment” is not the same as an obvious arithmetic mistake.

5. The buyer accepted additional goods or services

Sometimes the dispute is not really about changing the price of delivered goods. It is about extras.

Examples:

the buyer ordered 100 units but accepted 120 units;
the supplier also installed, assembled, or customized the goods;
emergency delivery was requested outside the agreed scope;
the buyer changed specifications after production began;
the buyer asked for split deliveries to multiple locations.

If the extras were requested or knowingly accepted, the supplier may be able to charge for them. But the supplier should still prove the buyer agreed to the additional scope or at least benefited from it with knowledge.

6. The transaction involves government procurement

For Philippine government contracts, price changes are much stricter.

Under Section 89 of Republic Act No. 12009, the New Government Procurement Act, bid prices for the given scope of work are generally fixed and not subject to price escalation during contract implementation. Price escalation may be considered only in limited circumstances, particularly for extraordinary increases in specific infrastructure components, subject to prior approval and the rules of the Government Procurement Policy Board.

For suppliers dealing with national government agencies, LGUs, GOCCs, SUCs, or other procuring entities, a post-delivery price increase is not simply a matter of sending a revised billing. It usually requires written contractual authority, compliance with procurement rules, and proper approval.

Consumer purchases: price tag, receipt, and DTI rules matter

If the buyer is an ordinary consumer and the supplier is a retailer or business establishment, consumer protection laws may apply.

The Consumer Act of the Philippines, Republic Act No. 7394, protects consumers against deceptive, unfair, and unconscionable sales acts or practices. You can read the law through the Consumer Act on Lawphil.

For retail transactions, price display rules are also important. DTI Administrative Order No. 09 requires price tags to clearly indicate the price of consumer products, including VAT and other charges per unit in pesos and centavos. It also provides that if there is inconsistency between the shelf price, product price, or scanned database price, the lowest price prevails. The rule is available through the Supreme Court E-Library copy of DTI Administrative Order No. 09.

This matters in real life. If a store displays one price, delivers the item, then later demands a higher price, the consumer can use the displayed price, receipt, invoice, order confirmation, and screenshots as evidence.

For basic necessities and prime commodities, the Price Act, Republic Act No. 7581 as amended by Republic Act No. 10623, may also apply during emergencies or price control situations. DTI’s e-Presyo system is commonly used to monitor prevailing prices and suggested retail prices for covered goods.

What buyers should do when a supplier demands a higher price after delivery

If you receive a revised invoice or demand letter after delivery, do not ignore it. But do not automatically pay it either.

Step 1: Gather all transaction documents

Collect and save:

quotation;
purchase order;
sales order;
supply agreement;
delivery receipt;
sales invoice or official receipt;
proof of payment;
emails and chat messages;
photos of delivered goods;
screenshots of online listings or product pages;
proof of posted price or shelf price, if applicable;
receiving report or acceptance form;
any written price adjustment clause.

For companies, also check internal documents such as canvass sheets, approval forms, procurement approvals, and accounts payable records.

Step 2: Identify the agreed price

Look for the document or message showing the clearest agreement on:

item or product description;
quantity;
unit price;
total price;
VAT treatment;
delivery charges;
payment terms;
delivery date;
validity period of quotation;
whether the price was fixed or subject to adjustment.

If the supplier’s new price contradicts the purchase order or accepted quotation, the buyer has a strong basis to object.

Step 3: Ask the supplier for the legal and contractual basis

A practical written response may say:

We received your revised invoice dated ____. We do not agree to the price increase. Please identify the specific contract provision, purchase order term, or written agreement authorizing the adjustment, and provide the computation and supporting documents.

This approach is calm, clear, and useful if the dispute later reaches mediation, barangay conciliation, DTI, or court.

Step 4: Pay the undisputed amount, if appropriate

If you agree that you owe the original contract price but dispute only the increase, consider paying the undisputed amount while clearly stating that the payment is without admission of the revised price.

For example:

Payment of ₱____ is made for the original agreed invoice amount only. We dispute the additional charge of ₱____ and do not accept the revised price.

This helps show good faith and may reduce the risk of being portrayed as a non-paying buyer.

Step 5: Object in writing before silence is used against you

Silence can create problems in business disputes, especially when parties have an ongoing relationship. If the supplier sends a revised invoice and the buyer keeps ordering, pays partially, or says “noted,” the supplier may later argue that the buyer accepted the new terms.

A clear written objection is often the simplest protection.

Step 6: Choose the correct dispute forum

The proper forum depends on the parties and amount involved.

Situation	Possible forum or process
Both parties are individuals residing in the same city or municipality	Barangay conciliation may be required first
Consumer complaint against a business	DTI Consumer Care / DTI mediation and adjudication
Money claim up to ₱1,000,000, exclusive of interest and costs	Small Claims Court in the first-level courts
Larger commercial claim or claim with damages/injunction	Regular civil action in the proper court
Government procurement contract	Contract dispute procedure, procurement rules, possible arbitration if applicable
Construction contract dispute	Possible Construction Industry Arbitration Commission jurisdiction, depending on the contract and parties

Under the Supreme Court Rules on Expedited Procedures in the First Level Courts, small claims cases cover purely civil claims for payment or reimbursement of money where the claim does not exceed ₱1,000,000, exclusive of interest and costs. Lawyers are generally not allowed to appear for parties during the small claims hearing, unless they are the plaintiff or defendant themselves.

Barangay conciliation: when it may be required before court

For disputes between individuals who reside in the same city or municipality, the Katarungang Pambarangay system under the Local Government Code may require barangay conciliation before filing in court.

In practical terms:

The complainant files a complaint with the proper barangay.
The Punong Barangay attempts mediation.
If mediation fails, the matter may go to the Pangkat ng Tagapagkasundo.
If settlement still fails, the barangay issues a Certification to File Action.
The party may then proceed to court, if appropriate.

Common bottlenecks include wrong barangay filing, incomplete addresses, non-appearance of parties, and failure to secure the proper certification. If one party is a corporation, partnership, or juridical entity, barangay conciliation may not apply in the same way because barangay proceedings generally involve natural persons.

DTI complaints for consumer transactions

If the buyer is a consumer dealing with a seller or supplier, a complaint may be filed through the DTI Consumer CARe System or the appropriate DTI office.

Useful documents include:

valid ID;
complaint narrative;
receipt or invoice;
proof of payment;
screenshots of advertised price;
photos of product and price tag;
delivery receipt;
warranty card, if any;
messages with the seller;
demand or revised billing from the supplier.

DTI usually starts with mediation. If settlement fails and the complaint falls within DTI jurisdiction, it may proceed to adjudication under DTI rules. For many consumers, DTI mediation is faster and less intimidating than immediately going to court.

Practical examples

Example 1: Construction materials delivered at agreed unit price

A homeowner orders tiles at ₱850 per box. The supplier confirms by text, delivers 80 boxes, and the homeowner signs the delivery receipt. Two days later, the supplier says the correct price should have been ₱920 because the supplier’s warehouse price changed.

The homeowner can refuse the increase unless the supplier proves there was a valid price adjustment clause, a genuine clerical error, or later acceptance by the homeowner.

Example 2: Imported equipment with foreign exchange clause

A company orders imported machine parts. The quotation says, “Final billing subject to USD-PHP exchange rate on date of customs release.” Delivery is completed and the supplier bills a higher peso amount because the exchange rate moved.

This may be valid if the formula was agreed beforehand and correctly applied.

Example 3: Online seller changes price after confirming order

A buyer purchases an appliance online at a confirmed price and receives it. The seller later says the listing price was wrong and asks for an additional payment.

If the transaction was confirmed, paid, and delivered, the seller will have difficulty imposing a higher price unless it can prove an obvious mistake and a valid legal basis for correction. If the buyer is a consumer, DTI rules and consumer protection principles may also help.

Example 4: Buyer accepted extra quantity

A restaurant ordered 50 kilos of meat but accepted 60 kilos, used the full delivery, and did not object. The supplier bills the extra 10 kilos.

That is not necessarily an illegal price change. It may be a valid charge for additional goods accepted by the buyer.

Example 5: Supplier sends revised invoice but buyer immediately objects

A supplier delivers office chairs under a purchase order of ₱3,500 per chair. After delivery, the supplier sends a revised invoice at ₱3,900 per chair. The buyer immediately replies that it rejects the increase and will pay only the purchase order price.

The buyer’s written objection helps prevent an argument that it accepted the revised price.

Common mistakes that make these disputes worse

Paying the higher amount without written protest

If you pay the revised invoice without objection, the supplier may argue that you accepted the new price. If you must pay to avoid business disruption, write that payment is under protest and specify what amount is disputed.

Signing a revised invoice casually

A signature can be used as evidence of acceptance. Before signing, write “received only, price disputed” if you are only acknowledging receipt.

Relying only on verbal agreements

Verbal agreements can be valid, but they are harder to prove. Confirm important points by email or message, especially unit price, VAT, delivery charges, and price adjustment terms.

Ignoring VAT and delivery charges

Many disputes are not about the base price but about whether the quoted amount was VAT-inclusive, VAT-exclusive, or separate from freight, handling, installation, or customs charges.

For consumer retail goods, price tags should already include VAT and other charges. For business-to-business transactions, the contract or quotation usually controls.

Continuing to order after objecting to the price increase

If you reject the increase but continue placing orders without clarifying the price, the supplier may argue that the higher price applies to later deliveries. State clearly whether your objection applies only to the completed delivery or also to future orders.

Documents that matter most in a post-delivery price dispute

Document	Why it matters
Quotation	Shows the supplier’s offered price and validity period
Purchase order	Shows buyer acceptance and agreed commercial terms
Sales invoice	Shows billed price, VAT, and item details
Delivery receipt	Shows what was delivered and accepted
Official receipt or proof of payment	Shows what was paid and when
Chat or email messages	Can prove agreement, objection, or later acceptance
Price list or online listing	Useful for consumer or retail disputes
Contract or terms and conditions	May contain escalation, tax, freight, or adjustment clauses
Receiving report	Important for companies and government procurement
Demand letter or revised invoice	Shows the supplier’s claim and timing

Can the supplier withhold future deliveries because the buyer refuses the increase?

For a completed delivery, the supplier generally cannot change that completed transaction unilaterally. But for future deliveries, the supplier may refuse new orders or quote new prices, unless there is an existing supply contract requiring continued delivery at fixed prices.

This distinction is important:

Completed delivery: usually governed by the already agreed price.
Future delivery: may be subject to new negotiation, unless locked in by contract.
Installment supply contract: depends on the wording of the agreement, including duration, price adjustment, termination, and default clauses.

Can the buyer return the goods instead of paying the increased price?

If the goods were validly delivered and accepted under the original price, the buyer normally does not need to return them just because the supplier later wants a higher price. The buyer should pay the agreed price.

Return may become relevant if:

there was no final agreement on price;
the goods do not match the order;
the buyer rejected delivery on time;
the supplier refuses to honor the original price and both parties agree to unwind the transaction;
consumer remedies such as refund, replacement, or repair apply.

Under Article 1235 of the Civil Code, if the creditor accepts incomplete or irregular performance without protest, the obligation may be deemed fully complied with. This principle can matter when a buyer accepts goods despite issues, or when a supplier accepts payment without reservation.

Frequently Asked Questions

Can a supplier increase the price after delivery in the Philippines?

Usually, no. If the price was already agreed and delivery was completed, the supplier cannot impose a higher price by itself. The supplier needs a valid basis such as a price adjustment clause, buyer approval, correction of an obvious error, or additional goods or services accepted by the buyer.

What if the supplier says its costs increased after I ordered?

A supplier’s increased cost does not automatically justify charging the buyer more after delivery. Business cost increases are generally the supplier’s risk unless the contract has a clear escalation clause or the buyer agreed to the adjustment.

Is a revised invoice enough to change the contract price?

No. A revised invoice is only the supplier’s billing document. It does not automatically amend the contract. The buyer’s agreement is still needed unless the revision is supported by the original contract or law.

What if I signed the delivery receipt?

Signing a delivery receipt usually proves that goods were received. It does not always prove agreement to a new price, especially if the delivery receipt does not state the increased price. But if the document you signed includes the revised price, the supplier may use it as evidence of acceptance.

Can I pay the original amount and refuse the increase?

Yes, if you genuinely agree that the original amount is due but dispute the added charge. It is best to state in writing that payment is for the original agreed price only and that you reject the additional amount.

Can the supplier charge interest on the increased amount?

The supplier can charge interest only if there is a legal or contractual basis. Under Article 1589 of the Civil Code, interest on the price after delivery generally applies if stipulated, if the thing sold produces fruits or income, or if the buyer is in default after judicial or extrajudicial demand.

What if there was no written contract?

A written contract is not always required. The agreed price may be proven through quotations, purchase orders, invoices, receipts, delivery documents, emails, chats, payment records, and the parties’ usual course of dealing.

Can I file a DTI complaint against a supplier who changed the price?

If you are a consumer dealing with a business, yes, a DTI complaint may be appropriate, especially if the issue involves misleading pricing, price tag discrepancies, online seller pricing, or unfair sales practices. If it is a purely commercial business-to-business collection dispute, court or contractual dispute resolution may be more appropriate.

Is this a small claims case?

It may be, if the dispute is a purely civil money claim not exceeding ₱1,000,000, exclusive of interest and costs. Small claims cases are filed in first-level courts such as the MeTC, MTCC, MTC, or MCTC, using Supreme Court forms.

What should I write to a supplier demanding a higher price?

A clear response is: “We do not agree to the price increase. Please identify the specific contract provision or written agreement authorizing the revised price and provide your computation. We remain willing to settle the original agreed amount of ₱____.” Keep the tone professional and save proof that the message was sent.

Key Takeaways

A supplier generally cannot change prices after completed delivery if the buyer and supplier already agreed on a fixed price.
Article 1308 of the Civil Code prevents one party from leaving contract compliance solely to its own will.
A price increase may be valid if there is a clear escalation clause, buyer approval, objective pricing formula, genuine billing error, or accepted additional goods or services.
A revised invoice alone does not amend the contract.
Buyers should object in writing, pay only undisputed amounts when appropriate, and keep all transaction records.
Consumers may consider DTI remedies; money claims up to ₱1,000,000 may fall under small claims; some disputes may require barangay conciliation first.
For government procurement, post-award price escalation is tightly controlled under RA 12009 and procurement rules.