If someone changes a signed quotation after you approved it—especially to increase the project price—you should treat it as a serious contract and evidence issue, not just an “accounting correction.” In the Philippines, a signed quotation can become a binding agreement when it shows the parties’ consent, the work or materials covered, and the agreed price. If the other party later alters the document without your authority, you may have civil remedies for breach of contract or damages, and in some cases criminal remedies for falsification, estafa, or cyber-related offenses.

Why an altered signed quotation matters

A quotation is often used in construction, renovation, fabrication, design, repair, supply, events, fit-outs, and professional services. Many people think it is “only a quote,” but once the customer accepts it and both sides act on it, it may function as the written evidence of the contract.

Common examples include:

A contractor changes a ₱450,000 signed renovation quotation to ₱650,000.
A supplier adds items or quantities after the customer signed.
A project manager replaces the final page of a signed quotation with a higher-cost version.
A quotation sent by email or PDF is edited after approval.
A contractor claims there was a “revised quotation,” but the customer never agreed to it.
A foreign client abroad signs a Philippine project quotation electronically, then receives a different version when billing starts.

The key question is not simply whether the price increased. The legal issue is whether the change was authorized, proven, and accepted.

A legitimate price adjustment can happen if both parties agreed to a variation order, change order, revised scope, or supplemental quotation. But a unilateral alteration of a signed document is different. It can affect consent, evidence, billing, and potential liability.

Is a signed quotation legally binding in the Philippines?

A signed quotation may be legally binding if it contains the basic elements of a contract.

Under the Civil Code of the Philippines, Republic Act No. 386, a contract is a meeting of minds between two persons where one binds himself to give something or render a service to another. The Civil Code also provides that contracts are perfected by consent, and that the essential requisites of a contract are consent, object, and cause.

In practical terms, a signed quotation is stronger if it clearly shows:

Contract element	What it means in a signed quotation
Consent	The customer accepted the quotation by signing, emailing approval, paying a down payment, or allowing work to start
Object	The specific project, service, materials, deliverables, location, or scope of work
Cause or consideration	The agreed price, payment terms, or reason each party agreed

A signed quotation may be treated as the contract itself, or as part of a larger agreement, together with purchase orders, invoices, receipts, emails, text messages, plans, specifications, and proof of payment.

Under Article 1159 of the Civil Code, obligations arising from contracts have the force of law between the parties and must be complied with in good faith. That means one party cannot simply rewrite the price after the other party has already accepted the original terms.

When is a price change valid?

A higher project cost is not automatically illegal. Projects can legitimately become more expensive when the scope changes.

A price change is usually valid when there is proof that:

The customer requested additional work, materials, upgrades, or revisions.
The contractor or supplier disclosed the added cost before doing the extra work.
The customer clearly approved the increase.
The approval can be proven through a signed change order, email, message, purchase order, payment, or other reliable evidence.
The new billing matches the approved additional scope.

For example, if you approved a ₱300,000 kitchen renovation quotation, then later asked for imported tiles, additional cabinets, and electrical upgrades, the contractor may charge more if those changes were agreed upon.

But if the contractor simply edits the original signed quotation and makes it appear that you approved the higher amount from the start, that is a different matter.

When is an altered quotation legally suspicious?

A signed quotation becomes legally suspicious when the change affects an important term and there is no clear proof of your consent.

Watch for these red flags:

The amount, quantities, unit prices, payment schedule, or scope changed after signing.
Your signature appears on a version you never saw.
Pages appear to have been replaced.
The font, spacing, alignment, date, initials, or page numbers look different.
The contractor says the change was “standard” or “automatic,” but cannot show written approval.
The other party refuses to provide the original file or email trail.
You are pressured to pay immediately despite disputing the alteration.
The revised amount appears only after you complained, delayed payment, or terminated the project.

A material alteration is especially serious when it changes the amount payable, the work covered, the deadline, warranties, penalties, or acceptance terms.

Your civil rights under Philippine contract law

If someone alters a signed quotation to increase project costs, your first remedies are usually civil. Civil remedies deal with money, performance, refund, cancellation, or damages.

You can insist on the original agreed price

If the original quotation was accepted and there is no valid approved revision, you can take the position that the enforceable agreement is the original signed quotation.

Article 1159 of the Civil Code supports the principle that contracts must be complied with in good faith. Article 1170 also provides that those who, in the performance of their obligations, are guilty of fraud, negligence, delay, or contravention of the tenor of their obligations are liable for damages.

In plain English: if the other party changes the deal without your consent and causes you loss, you may have a claim for damages.

You can dispute the excess billing

You do not have to silently accept a higher bill just because the other party presents an edited quotation.

You can dispute:

The unauthorized increase;
Items not included in the original scope;
Charges not supported by receipts, delivery records, or approved change orders;
Duplicate items;
Inflated quantities;
Unapproved mobilization, supervision, or miscellaneous charges;
Penalties or interest not agreed upon.

When disputing a bill, be specific. Do not simply say “This is wrong.” Identify the original price, the altered price, the exact items changed, and the documents proving your position.

You can seek rescission or cancellation in serious cases

Article 1191 of the Civil Code allows the injured party in reciprocal obligations to choose between fulfillment and rescission, with damages in either case, when the other party does not comply with what is incumbent upon him.

For project disputes, this may apply when the alteration is part of a larger breach, such as:

Refusal to continue unless you pay the altered amount;
Abandonment of work;
Substandard or incomplete work;
Charging for materials never delivered;
Using the altered quotation to justify overbilling.

Rescission is not automatic in every disagreement. Courts look at the seriousness of the breach, the evidence, and the conduct of both parties.

You can claim damages

Depending on the facts, damages may include:

Refund of overpayment;
Cost of hiring another contractor to finish or correct the work;
Cost of replacing defective materials;
Liquidated damages if stated in the contract;
Actual damages supported by receipts;
Attorney’s fees when recoverable under the Civil Code or contract;
Interest, if legally or contractually proper.

Keep receipts, photos, site inspection reports, delivery records, and communications. Philippine courts and prosecutors rely heavily on documents.

Possible criminal liability: falsification, estafa, and cybercrime

Not every contract dispute is a crime. Prosecutors are careful about turning business disagreements into criminal cases. But altering a signed quotation can become criminal when there is fraud, falsification, deceit, or use of a falsified document.

Falsification under the Revised Penal Code

Under the Revised Penal Code, falsification may apply when a person alters a document or makes it appear that someone participated in an act or statement when that person did not.

Article 172 punishes falsification by private individuals and use of falsified documents. Article 171 lists acts of falsification, including making alterations or intercalations in a genuine document that change its meaning.

For a signed quotation, possible falsification issues may arise if someone:

Changes the price after signing;
Adds line items after approval;
Replaces a page but keeps your signature page;
Copies your signature onto another quotation;
Makes it appear that you approved a revised quotation;
Uses the altered document to demand payment, collect money, or justify withholding work.

A quotation may be treated as a private document or, depending on its nature and use, a commercial document. This distinction matters because the elements and proof required can differ. For private documents, damage or intent to cause damage is important.

Estafa under Article 315

Estafa, or swindling, under Article 315 of the Revised Penal Code may apply when deceit causes another person to part with money or property.

In this kind of dispute, estafa may be considered if the altered quotation was used to induce payment, obtain additional money, or make the customer believe the higher amount was previously approved.

Typical estafa-related scenarios include:

The contractor presents the altered quotation and says, “This is what you signed.”
The customer pays the increased amount because of the false document.
The contractor uses the edited quotation to collect a higher down payment.
The supplier refuses delivery unless the customer pays the altered amount.

The timing of deceit matters. Prosecutors usually examine whether the fraudulent representation happened before or at the time the money was obtained, and whether it caused the offended party to suffer damage.

Cybercrime issues for edited digital quotations

If the quotation was altered electronically, additional issues may arise under the Electronic Commerce Act of 2000, Republic Act No. 8792, the Rules on Electronic Evidence, and possibly the Cybercrime Prevention Act of 2012, Republic Act No. 10175.

RA 8792 recognizes electronic documents and electronic signatures. It also provides that electronic documents cannot be denied admissibility solely because they are electronic. In practice, this means emails, PDFs, screenshots, project management records, and digital approvals can matter.

For digital evidence, preserve:

Original emails with headers;
PDF metadata, if available;
Messaging app export files;
Cloud storage version history;
E-signature audit trails;
File creation and modification dates;
Payment platform records;
Screenshots plus the actual device or account where messages are stored.

Screenshots help, but they are weaker if you cannot show where they came from. Courts give more weight to evidence that can be authenticated.

What to do immediately if your signed quotation was altered

1. Stop relying on verbal conversations

Once you suspect alteration, move important communications to writing.

Use email, text, Viber, WhatsApp, Messenger, or registered mail. Keep your tone calm and factual. Avoid threats, insults, or public accusations that could create defamation issues.

2. Secure the original signed quotation

Look for every copy of the original quotation:

The signed hard copy;
The PDF attached to the original email;
The photo or scan taken on signing day;
The contractor’s original message sending the quote;
Your reply accepting it;
The receipt showing the down payment based on the original amount;
Any purchase order or acknowledgment.

Do not write on the original document. Keep it clean, flat, and safely stored.

3. Compare the original and altered versions

Make a side-by-side comparison.

Focus on:

Item to compare	Why it matters
Total contract price	Shows the amount allegedly changed
Unit prices	Reveals hidden increases even if total is unclear
Quantities	Common place for inflated costs
Scope of work	Shows if new items were inserted
Payment milestones	May show earlier or larger payment demands
Dates	May show backdating or false revision history
Page numbers	Helps detect replaced pages
Initials and signatures	Shows whether changes were approved

Create a simple table listing each discrepancy. This becomes useful for barangay conciliation, demand letters, mediation, police complaints, prosecutor’s affidavits, or court filings.

4. Ask for the basis of the revised amount

Send a written request asking the other party to identify:

Who made the revision;
When it was made;
What specific scope change justified it;
Where your approval appears;
Whether there is a signed change order;
Whether there are receipts or delivery records for added items.

This forces the other side to commit to a version of events.

5. Send a written notice disputing the alteration

A clear written dispute helps protect you from arguments that you accepted the increased price by silence.

Your notice can state:

You approved only the original quotation dated a specific date;
You did not authorize the revised amount;
You request correction of the billing;
You reserve your rights to pursue civil, administrative, or criminal remedies;
You are willing to pay undisputed amounts, if any, under the original agreement;
You request all supporting documents within a reasonable period.

For significant amounts, have the letter sent by registered mail, courier with proof of delivery, or email with delivery/read confirmation. A notarized demand letter is not always required, but it can make the document more formal and easier to use later.

6. Do not pay the disputed increase without written reservation

If you must pay something to prevent greater damage—for example, to release materials or avoid project abandonment—make it clear in writing that the payment is made under protest and does not mean you accept the altered quotation.

Use language such as:

“This payment is made under protest and without admission that the revised quotation is valid. I reserve all rights to dispute the unauthorized increase and recover any overpayment.”

This is important because the other side may later argue that your payment confirmed acceptance.

7. Preserve digital evidence properly

Do not delete chats, emails, call logs, or project group messages.

For important digital evidence:

Export conversations where possible.
Take screenshots showing the sender, date, time, and surrounding messages.
Save files in their original format.
Back up files to a secure drive.
Avoid editing the file names or contents.
Keep the device or account available in case authentication is needed.

If the amount is large, consider having key screenshots printed and attached to a notarized affidavit explaining how and when they were obtained.

Where to file a complaint in the Philippines

The correct forum depends on the amount, location, parties, and remedy you want.

Situation	Possible forum or office	Practical notes
You want to settle first and both parties are individuals in the same city or municipality	Barangay conciliation	Often required before court action under the Katarungang Pambarangay system
You want to recover money not exceeding ₱1,000,000	Small Claims Court in the appropriate first-level court	Lawyers generally do not appear for parties at the hearing; process is simplified
You want damages, rescission, injunction, or claims beyond small claims coverage	Regular civil action in court	May require lawyer preparation and formal pleadings
You believe a crime was committed	Police, NBI, or City/Provincial Prosecutor	Requires affidavits and evidence; prosecutor determines probable cause
The contractor is licensed or should be licensed by PCAB	PCAB/CIAP-related complaint or verification	Useful for construction contractor accountability
The dispute involves consumer goods or services	DTI complaint/mediation	May help in consumer-facing transactions, depending on the facts
The contract has an arbitration clause for construction disputes	CIAC arbitration may apply	Construction disputes may be covered if there is an arbitration agreement or legal basis

Barangay conciliation

The Katarungang Pambarangay system under the Local Government Code generally requires certain disputes between residents of the same city or municipality to go through barangay conciliation before filing in court. The Supreme Court’s guidance on barangay conciliation recognizes it as a pre-condition for many court actions, subject to exceptions.

In practice, barangay proceedings are faster and less formal. You usually bring:

Copies of the original and altered quotation;
Receipts and proof of payment;
Messages and emails;
Photos of work done;
A written summary of your complaint;
Valid IDs.

If settlement fails, the barangay may issue a Certificate to File Action, which may be needed before proceeding to court.

Small claims court

The Supreme Court has increased the small claims threshold to ₱1,000,000, with coverage for certain money claims such as contracts of services, sale of personal property, loans, leases, and enforcement of barangay settlements or arbitration awards. The Supreme Court’s rules on expedited procedures also state that small claims decisions of first-level courts are final, executory, and unappealable.

Small claims can be useful if your goal is simple: recover money or collect a definite amount.

It may not be the best fit if you need:

An injunction;
Detailed technical construction findings;
Rescission of a complex contract;
Extensive expert testimony;
Criminal prosecution;
Claims above the small claims limit.

Prosecutor’s office for criminal complaints

For falsification or estafa, the usual route is to file a complaint-affidavit before the Office of the City or Provincial Prosecutor, often after police or NBI assistance.

You generally need:

Complaint-affidavit narrating what happened;
Original and altered quotations;
Proof of payment or attempted collection;
Emails, messages, and screenshots;
IDs of the complainant;
Witness affidavits, if any;
Business records, receipts, photos, and delivery documents;
Certification or explanation of digital evidence, when relevant.

The prosecutor will require the respondent to submit a counter-affidavit. After preliminary investigation, the prosecutor may dismiss the complaint or file an Information in court if probable cause exists.

Special issues in construction and renovation projects

Altered quotations often happen in construction-related disputes because project costs can genuinely change. This makes documentation extremely important.

Check if the contractor is licensed

For construction work, the Contractors’ License Law, Republic Act No. 4566, as amended, created the licensing framework for contractors. The Philippine Contractors Accreditation Board, under the Construction Industry Authority of the Philippines, handles contractor licensing. PCAB describes itself as an agency attached to the Department of Trade and Industry and an implementing board of CIAP.

You can use the official CIAP website and PCAB portal to check licensing-related information or available services.

A contractor’s license issue does not automatically prove that a quotation was altered, but it may be relevant if the contractor is operating without proper authority or is engaged in repeated improper practices.

Separate legitimate variation orders from unauthorized changes

A legitimate variation order usually has:

A description of added or deducted work;
Cost impact;
Time impact;
Date of approval;
Signature or written approval of the owner/client;
Reference to the original contract or quotation.

An unauthorized alteration usually has:

No separate approval;
No clear date of revision;
No supporting receipts or delivery records;
A changed total price inserted into the original document;
Pressure to accept the edited version after the fact.

If you requested extra work verbally, the contractor may argue that the higher amount reflects your instructions. Your evidence should show whether you agreed only to the work, or also to the added cost.

What documents should you prepare?

Before going to barangay, court, police, prosecutor, DTI, PCAB, or CIAP, organize your documents.

Document	Why it helps
Original signed quotation	Shows the agreed price and scope
Altered quotation	Shows the disputed changes
Emails and messages	Establish negotiation, approval, and objections
Receipts and bank transfers	Prove payments and reliance on the original price
Photos or videos of project progress	Useful for construction or service disputes
Delivery receipts and purchase records	Confirm whether materials were actually supplied
Demand letter or dispute notice	Shows you objected and did not accept the alteration
Barangay records	May be required before court filing
Affidavits of witnesses	Helpful if others saw the signing or negotiations
Contractor license details	Relevant for construction-related complaints
E-signature audit trail	Important for electronically signed quotations

For foreign clients, documents signed abroad may need extra care. If a document will be used in Philippine proceedings and it was notarized abroad, it may need an apostille if issued in a country that is part of the Apostille Convention, or consular authentication if not covered. If the document is in a foreign language, a translation may be needed.

Practical timelines to expect

Timelines vary by city, court, agency workload, and complexity, but these are common practical ranges:

Step	Usual practical timeline
Gathering documents and sending dispute notice	A few days to 2 weeks
Barangay conciliation	Often several weeks, depending on schedules
Small claims filing to hearing	Often faster than ordinary civil cases, but depends on court docket and service of summons
Prosecutor preliminary investigation	Several months is common
Regular civil case	Can take years, especially if evidence is technical or heavily contested
Construction arbitration or mediation	Often faster than ordinary trial, depending on forum and complexity

A common bottleneck is service of summons or notices. If the contractor avoids receiving papers, changed address, or uses only a trade name without clear registration details, the case can slow down.

Common mistakes to avoid

Paying the increased amount just to “avoid trouble”

Payment can be used against you as evidence of acceptance. If payment is unavoidable, put your protest in writing.

Relying only on screenshots

Screenshots are useful, but preserve the original messages and files. If possible, export chats and save emails with headers.

Posting accusations online

Calling someone a scammer or falsifier online before a legal finding can expose you to libel or cyber libel complaints. Keep disputes factual and direct them to the proper forum.

Ignoring barangay requirements

If barangay conciliation is required and you skip it, your court case may face dismissal or delay.

Filing a criminal complaint with weak evidence

A criminal complaint should be supported by clear documents showing alteration, use, deceit, and damage. A mere disagreement over final billing may not be enough.

Failing to distinguish “altered quotation” from “new scope”

If you asked for additional work, be ready to explain what was authorized, what was not, and whether the price was agreed.

Frequently Asked Questions

Can a contractor increase the price after I signed the quotation?

Yes, but only if there is a valid basis, such as an agreed change in scope, added materials, or a written price adjustment. A contractor generally cannot unilaterally change a signed quotation and claim you agreed to the higher amount without proof of your consent.

Is changing a signed quotation falsification in the Philippines?

It can be, depending on the facts. If someone alters a genuine document in a way that changes its meaning, makes it appear that you agreed to terms you did not approve, and uses it to cause damage or obtain payment, falsification under the Revised Penal Code may be considered. The prosecutor will evaluate the evidence.

What if I signed only the last page and they changed the earlier pages?

That is a common risk. If earlier pages were replaced or edited after signing, compare page numbers, formatting, scope, totals, initials, email attachments, and file history. In future transactions, initial every page and keep a scanned copy immediately after signing.

Can emails or Viber messages prove the original quotation?

Yes. Electronic documents and electronic signatures are recognized under Philippine law, including RA 8792 and the Rules on Electronic Evidence. Preserve the original account, message thread, timestamps, attachments, and surrounding conversation so the evidence can be authenticated.

Should I go to the barangay first?

If both parties are natural persons residing in the same city or municipality, barangay conciliation may be required before filing a court case, unless an exception applies. If one party is a corporation, partnership, or non-resident in a way that removes the dispute from barangay coverage, the analysis may differ.

Can I file a small claims case for the overcharged amount?

Yes, if your claim is a covered money claim and the amount does not exceed the current small claims threshold of ₱1,000,000, exclusive of interest and costs. Small claims is useful for recovering money but may not fit complex cases requiring injunctions, technical construction findings, or criminal prosecution.

What if I already paid the higher amount?

You may still dispute it if you can show you paid because of fraud, pressure, mistake, or reliance on an altered document. Gather proof of the original quotation, the altered version, payment records, and communications. Send a written demand for refund or correction before filing the appropriate complaint.

What if the contractor says the increase was due to material price changes?

Material price increases may justify an adjustment only if the contract allows it or you agreed to it. Ask for supplier receipts, delivery records, dates, and written approval of the price change. A general claim that “materials became expensive” does not automatically amend a signed quotation.

Can a foreigner file a complaint in the Philippines?

Yes. A foreigner dealing with a Philippine project may file civil, criminal, administrative, or arbitration-related complaints when legally proper. The main practical issues are documentation, notarization or apostille for documents executed abroad, representation, hearing attendance, and proving communications across countries.

What is the strongest evidence in an altered quotation dispute?

The strongest evidence is usually the original signed quotation, the altered version, proof of when each was sent or received, payment records, written objections, and messages showing whether any revision was approved. For digital files, email headers, audit trails, metadata, and cloud version history can be very helpful.

Key Takeaways

A signed quotation can be legally binding in the Philippines if it shows consent, scope, and price.
A contractor, supplier, or service provider cannot simply alter a signed quotation to increase project costs without your consent.
Legitimate price increases should be supported by approved change orders, revised quotations, or clear written authorization.
Unauthorized alteration may lead to civil claims for breach of contract, refund, damages, rescission, or specific performance.
In serious cases, falsification, estafa, or cybercrime-related issues may arise.
Preserve the original quotation, altered version, emails, messages, receipts, and digital file history.
Dispute the alteration in writing and avoid paying the increased amount unless you clearly state that payment is under protest.
Barangay conciliation, small claims court, regular civil action, prosecutor complaints, DTI, PCAB, CIAP, or CIAC may be relevant depending on the facts.
For construction projects, always require written variation orders before accepting additional costs.
The best protection is simple: sign every page, keep a copy immediately, document all changes, and never rely on verbal approval for added project costs.