Quick answer

Generally, no. If a contractor agreed to complete a defined scope of work for a fixed or lump-sum price based on agreed plans and specifications, the contractor normally cannot increase that price merely because labor, cement, steel, fuel, equipment, or other inputs became more expensive.

Article 1724 of the Civil Code allows additional payment for changed or additional work only when:

The owner authorized the change in writing; and
The additional price was determined in writing by both parties.

More may also be payable if the contract itself contains a valid price-adjustment mechanism, the claimed work was clearly excluded from the original scope, or the arrangement was not truly a fixed-price contract with definite plans and specifications. Claims arising from owner-caused delay, nonpayment, or another breach require a separate contractual and factual analysis.

A contractor may send a demand, but a demand is not automatically legally enforceable.

The general rule for fixed-price work

Article 1724 applies when a contractor undertakes to build a structure or perform other work:

For a stipulated price; and
In accordance with plans and specifications agreed upon with the owner.

In that situation, the contractor generally assumes the ordinary pricing risk. A mistake in estimating quantities, unexpectedly low productivity, or an ordinary increase in material or labor costs does not, by itself, transfer the loss to the owner.

The Supreme Court applied this rule in Leighton Contractors Philippines, Inc. v. CNP Industries, Inc., G.R. No. 160972, March 9, 2010. It explained that a fixed lump-sum contractor estimates the project based on its scope and schedule and accounts for probable measurement errors and price changes. Where disputed items were already within the contracted scope, the owner was liable only for the stipulated price.

The rule applies to both project owners and, when the facts fit Article 1724, contractors and subcontractors working under fixed lump-sum arrangements.

When additional payment may be valid

A properly documented change in the work

The clearest basis for an increase is a valid change order, variation order, extra-work order, or supplemental agreement satisfying both requirements of Article 1724.

There should be:

A written instruction or authorization from the owner or an authorized representative identifying the changed or additional work; and
A written agreement between the parties stating the additional price or an agreed method that determines it.

In Filinvest Alabang, Inc. v. Century Iron Works, Inc., G.R. No. 213229, December 9, 2015, additional work was recoverable because written site instructions authorized it and written cost documents, using previously agreed rates, established its valuation.

The safest practice is to sign the complete change order before the contractor starts the extra work. It should state:

The exact additional, omitted, or revised work;
The agreed price or valuation formula;
Any change in the completion date;
Any effect on warranties, retention, or payment milestones; and
The names and authority of the signatories.

An express price-adjustment clause

Some contracts are described as “fixed price” but contain limited adjustment provisions, such as:

An escalation formula tied to a specified index;
Adjustments for newly imposed taxes or wage orders;
Foreign-exchange adjustments;
Provisional sums or allowances;
Unit-price remeasurement for identified items; or
A hardship or extraordinary-event clause.

Contractual obligations generally have the force of law between the parties under Article 1159 of the Civil Code. An adjustment is enforceable only if the contract actually permits it and the stated trigger, notice, computation, documentation, and approval requirements are satisfied.

A clause allowing adjustment does not give the contractor a free hand to choose a new price. The contractor must use the agreed mechanism.

Work outside the original scope

A fixed price covers the scope for which it was agreed. It does not automatically include every task later requested by the owner.

Determining whether work is genuinely additional requires examination of all incorporated documents, including:

The signed agreement and notice of award;
Plans and technical specifications;
Scope-of-work descriptions;
Bills of quantities and schedules of rates;
The contractor’s proposal and listed exclusions;
Addenda, bid clarifications, and meeting records; and
Later drawing revisions and site instructions.

Calling work an “extra” does not make it one. Conversely, an owner cannot avoid paying for a genuine, properly authorized addition merely by pointing to the words “lump sum.”

No actual fixed price or no definite agreed scope

Article 1724 does not make a price immutable unless there was an actual stipulated price and definite, agreed plans and specifications. In CE Construction Corporation v. Araneta Center, Inc., G.R. No. 192725, August 9, 2017, the Supreme Court emphasized these requirements where the design and scope had been substantially revised and no definite price governed the disputed work.

A cost-plus, time-and-materials, unit-price, or remeasurement contract may therefore produce a final amount higher than an initial estimate. The contract’s substance—not merely its label—controls.

A separate claim arising from the owner’s breach

A demand caused by nonpayment, owner-caused delay, denied site access, late owner-supplied materials, or wrongful suspension is not necessarily a request to increase the fixed price because inputs became more expensive. It may instead be a claim for unpaid billings, extension costs, or damages under the contract and the general law on obligations.

Such a claim still depends on proof, causation, contractual risk allocation, notice requirements, and any limitation or exclusion of damages. The contractor should not simply add an unexplained amount to the contract price.

What is usually not enough

The following ordinarily do not establish a right to additional payment on their own:

A supplier’s later price increase;
Inflation or unfavorable exchange-rate movement;
A contractor’s estimating or quantity error;
An invoice issued only after extra work was completed;
Oral instructions unsupported by the writings Article 1724 requires;
The owner’s silence or presence while work was performed;
A progress report signed by someone without authority to approve changes or costs;
Payment of some change orders, offered as proof that all other changes were approved;
A contractor’s assertion that the increase is “standard industry practice”; or
An arbitrary percentage added to the contract price.

In Chung v. Ulanday Construction, Inc., G.R. No. 156038, October 11, 2010, the Supreme Court held that mere tolerance and payment of certain change orders did not establish liability for other unauthorized changes. The statutory requirement of written consent could not be replaced by equitable estoppel.

Emails, chat messages, electronic approvals, and electronically signed documents may raise separate questions about authenticity, completeness, authority, and compliance with the contract. Do not assume that an informal message satisfies Article 1724. Use a formal signed change order whenever possible.

What an owner should do after receiving a demand

Do not ignore it. Ask for a complete written computation and the exact contractual basis for every item.
Separate the claims. Distinguish among the original contract balance, retention, approved change orders, disputed extra work, escalation, delay costs, interest, and damages.
Compare the claimed work with the original scope. Review every incorporated plan, specification, exclusion, bill of quantities, and revision.
Check the writings. Identify the document that supposedly authorized each change and the document showing agreement on its price.
Verify authority. Confirm that the person issuing or signing the instruction had authority under the contract or a valid written delegation.
Respond in writing. State which amounts are admitted, disputed, or awaiting documents. Reserve rights and avoid language that unintentionally acknowledges a disputed debt.
Pay undisputed amounts when due. A disputed extra does not automatically excuse withholding valid progress billings or other amounts already payable under the contract.
Document the current site condition. Preserve dated photographs, inspection reports, accomplishment measurements, and records of materials already delivered.
Use the agreed dispute process. Follow any negotiation, engineer’s determination, mediation, arbitration, notice, or cure procedure in the contract.

An owner should not approve a change while leaving the price to be decided later unless the contract provides a clear valuation method. “Proceed now; we will discuss the cost later” is a common source of expensive disputes.

What a contractor should do before performing extra work

Give the notice required by the contract as soon as a possible change is identified.
Describe why the requested work is outside or different from the original scope.
Submit a detailed proposal showing quantities, rates, labor, materials, equipment, taxes, markups, schedule effects, and supporting documents.
Obtain written authorization from the owner or the specifically authorized representative.
Obtain written agreement on the additional price or the contractually permitted valuation formula.
Record any extension of time together with the price adjustment.
Keep the extra work and its costs separately identifiable in daily reports, payrolls, delivery receipts, invoices, and accomplishment measurements.
Do not rely only on oral instructions from an architect, engineer, foreman, property manager, or site representative. Confirm that the person has authority to bind the owner.
If urgent work is needed to protect life, property, or the works, document the emergency, give immediate written notice, and seek formal confirmation. Emergency action does not automatically settle who must bear the cost.

A contractor should not abandon or suspend the project merely because its costs increased. In Ong v. Bogñalbal, G.R. No. 149140, September 12, 2006, the Court distinguished withdrawal caused by increased costs from a dispute based on the owner’s alleged failure to pay. Any suspension or termination should follow the applicable contract provisions and general rules on reciprocal obligations.

Evidence both sides should preserve

Keep original and backed-up copies of:

The signed contract and all annexes;
Proposals, quotations, exclusions, and bid clarifications;
Plans, specifications, and every dated drawing revision;
Bills of quantities and schedules of rates;
Change orders, variation orders, and site instructions;
Documents showing each signatory’s authority;
Emails, messages, meeting minutes, and transmittal records;
Daily site logs and accomplishment reports;
Dated photographs and videos;
Inspection, testing, and punch-list reports;
Payrolls, purchase orders, supplier invoices, and delivery receipts;
Progress billings, official receipts, and payment records;
Delay notices and requests for extensions;
Certificates of completion, turnover, and acceptance;
Warranty, retention, bond, and insurance documents; and
All demand letters and proof of delivery or receipt.

Preserve native electronic files and metadata where available. A screenshot may omit dates, participants, attachments, or the surrounding conversation.

Special rule for government infrastructure projects

Government contracts are subject to procurement law, their bidding documents, and special approval procedures in addition to ordinary contract principles.

Section 89 of Republic Act No. 12009, the New Government Procurement Act, treats bid prices for the awarded scope as fixed during implementation. For infrastructure projects, price escalation may be considered only for an extraordinary increase in specific construction components, subject to prior GPPB approval. The statute uses a threshold of more than 10% of the unit price of work items, measured against applicable Philippine Statistics Authority price indices, and permits adjustment only on a no-loss, no-gain basis using the prescribed formula.

That threshold does not create an automatic entitlement. The contractor must satisfy the law, the implementing rules, applicable GPPB guidelines, approval requirements, and the particular contract documents. Transitional rules may also matter for procurements commenced under the previous regime.

The 10% statutory threshold for this special public-procurement situation is not a general rule allowing a private residential or commercial contractor to exceed a fixed price by 10%.

Disputes, filing routes, and deadlines

First read the dispute-resolution clause. Construction disputes involving payment, changes in contract cost, specifications, delays, and breach may fall within the Construction Industry Arbitration Commission’s jurisdiction when the parties are bound by an agreement to submit construction disputes to arbitration.

Section 4 of Executive Order No. 1008 covers disputes connected with Philippine construction contracts, whether arising before or after completion, abandonment, or breach. Parties considering arbitration should consult the CIAC’s current Revised Rules of Procedure and official forms. Without an applicable arbitration agreement, the proper remedy may be in court, subject to jurisdiction, venue, and any required pre-filing process.

There is no single statutory deadline for approving or rejecting every private change-order claim. The contract may impose much shorter notice or submission periods, sometimes as conditions to payment. Act promptly.

As an outer limitation, Civil Code Article 1144 generally gives ten years from accrual for an action upon a written contract, while Article 1145 generally gives six years for an action upon an oral contract. Special laws, the nature of the claim, arbitration rules, and contractual notice requirements may produce a different result. Under Article 1155, prescription may be interrupted by filing an action, a creditor’s written extrajudicial demand, or the debtor’s written acknowledgment of the debt. Do not wait for the general period to expire before seeking advice.

Common mistakes

Treating an estimate and a guaranteed lump sum as the same thing;
Signing a contract without attaching the final plans and specifications;
Using “fixed price” while leaving major allowances, exclusions, or quantities undefined;
Proceeding with verbal variations;
Agreeing to a change without settling its schedule impact;
Letting an unauthorized site representative approve substantial costs;
Combining valid base-contract billings with disputed extras in one unexplained demand;
Withholding all payments because one item is disputed;
Assuming acceptance of one change order approves every change;
Failing to comply with contractual notice deadlines;
Destroying earlier drawing versions or message threads; and
Stopping work without following notice, cure, suspension, and safety procedures.

When legal help is urgent

Consult a Philippine construction lawyer promptly if:

A contractor threatens immediate abandonment or removal of installed work;
An owner threatens lockout, termination, bond calls, or seizure of equipment;
Major structural work was changed without clear written approval;
The parties dispute whether a document or electronic message is binding;
The demand includes substantial delay costs, liquidated damages, interest, or loss-of-profit claims;
A contractual notice, arbitration, prescription, or court deadline is approaching;
The project is government-funded;
There are safety defects or risks to occupants, workers, or neighboring property;
Completion, acceptance, retention, or warranty documents are about to be signed; or
Either side is being asked to sign a waiver, quitclaim, final account, or settlement.

Frequently asked questions

Can a contractor charge more because cement or steel prices increased?

Generally, no—not under a genuine fixed-price contract with agreed plans and specifications. A contractual escalation clause or the special rules for qualified government infrastructure projects may change the result.

Is the owner’s verbal approval enough?

Ordinarily, no. Article 1724 requires written owner authorization for the change and a written determination of the additional price by both parties.

Does the document have to be called a “change order”?

Not necessarily. Courts examine the substance of the writings. Together, they must clearly establish authorized additional or changed work and written agreement on its price. A formal signed change order remains the safest document.

Can the contractor charge for work the owner requested but whose price was never agreed?

Recovery is legally vulnerable under Article 1724 when the additional price was not determined in writing by both parties. The precise result depends on the complete documents and whether an agreed rate or valuation mechanism already governed the work.

Can the owner require extra work without paying?

Not merely by relying on the original lump-sum amount. Genuine work outside the agreed scope should be addressed through a properly documented change. The contractor, however, must comply with Article 1724 and the contract’s change procedure.

Can the owner refuse the entire final billing?

Not automatically. The owner should separate valid unpaid contract amounts from genuinely disputed extras, defects, deductions, or counterclaims. Wrongful withholding may itself constitute breach.

Does force majeure automatically increase the price?

No. A fortuitous event may affect liability, time, suspension, or performance depending on the contract and Article 1174 of the Civil Code, but it does not automatically rewrite a fixed price.

Is there a general 10% allowance for private construction contracts?

No. The 10% threshold in Republic Act No. 12009 concerns possible escalation for qualifying government infrastructure projects and remains subject to statutory conditions and prior approval.

Official legal sources

This article provides general Philippine legal information, not advice for a specific contract or dispute. Enforceability depends on the complete agreement, incorporated documents, communications, authority of the signatories, project type, and applicable procedural rules. Primary legal sources were checked as of August 25, 2026.