Receiving a BIR Preliminary Assessment Notice can feel alarming because it usually contains proposed deficiency taxes, interest, surcharges, and legal references that are hard to read under time pressure. The most important thing to know is this: a PAN is not yet the final tax assessment, but it is a critical stage where you have a short window to answer, correct the BIR’s findings, and preserve your position before the Bureau of Internal Revenue issues a Formal Letter of Demand and Final Assessment Notice.

What Is a BIR Preliminary Assessment Notice?

A Preliminary Assessment Notice, or PAN, is the BIR’s written notice that it has found sufficient basis to propose a deficiency tax assessment after reviewing your tax returns, books, invoices, withholding tax records, VAT records, or other documents.

Under Section 228 of the National Internal Revenue Code of 1997, as amended by Republic Act No. 8424 and later tax laws, the taxpayer must be informed in writing of the law and facts on which an assessment is based; otherwise, the assessment may be void. The BIR’s due process rules are implemented mainly through Revenue Regulations No. 12-99, as amended by Revenue Regulations No. 18-2013 and later issuances. (Lawphil)

A valid PAN should not merely say “you owe this amount.” It should show the facts, law, rules and regulations, or jurisprudence supporting the proposed assessment. BIR RR No. 18-2013 expressly requires the PAN to show these bases in detail.

In everyday language, many taxpayers say they want to “protest a PAN.” Technically, however, the formal administrative protest is filed against the FLD/FAN, not the PAN. For a PAN, the proper filing is usually called a reply, response, or answer to the PAN.

PAN Reply vs. Formal Protest: Why the Difference Matters

The distinction is important because the deadlines and legal effects are different.

Stage	What you received	What you file	Deadline	Main consequence if ignored
Preliminary stage	PAN	Reply or response to PAN	15 days from receipt	BIR may treat you as in default and issue the FLD/FAN
Final assessment stage	FLD/FAN	Administrative protest: reconsideration or reinvestigation	30 days from receipt	Assessment becomes final, executory, and demandable
After protest	FDDA or BIR inaction	Appeal to CTA, or other available administrative remedy depending on who issued the decision	Usually 30 days from the relevant event	Loss of remedy if the period lapses

BIR RR No. 18-2013 states that if the taxpayer fails to respond within 15 days from receipt of the PAN, the taxpayer is considered in default, and a Formal Letter of Demand and Final Assessment Notice may be issued.

Once the FLD/FAN is issued, the taxpayer or authorized representative may file an administrative protest within 30 days from receipt, either as a request for reconsideration or a request for reinvestigation.

When the BIR May Issue a Final Assessment Without a PAN

A PAN is generally required, but Section 228 and the BIR regulations allow the BIR to issue an FLD/FAN outright in specific cases. Under RR No. 18-2013, a PAN is not required when the deficiency tax results from:

A mathematical error appearing on the face of the return;
A discrepancy between tax withheld and the amount actually remitted by the withholding agent;
Improper carry-over of excess creditable withholding tax after claiming refund or tax credit;
Non-payment of excise tax due on excisable articles;
Sale, transfer, or trade of an article purchased or imported by an exempt person to a non-exempt person.

For most ordinary BIR audits involving income tax, VAT, percentage tax, withholding tax, documentary stamp tax, or improperly supported deductions, the taxpayer should normally expect a PAN before the final assessment.

Your Key Rights When You Receive a PAN

You Have the Right to Written Facts and Legal Bases

The Supreme Court has repeatedly emphasized that tax assessment due process is not a mere formality. In Commissioner of Internal Revenue v. Fitness by Design, Inc., the Court explained that the taxpayer must be informed of the factual and legal bases of the assessment so the taxpayer can make an effective protest or appeal. Merely providing figures without sufficient explanation is not enough. (Supreme Court E-Library)

In Commissioner of Internal Revenue v. Liquigaz Philippines Corporation, the Supreme Court likewise held that the requirement to state the facts and law applies to the FLD/FAN and the Final Decision on Disputed Assessment, and failure to do so may invalidate the FDDA. (Supreme Court E-Library)

You Have the Right to Proper Service

Service of the PAN matters because the deadline is counted from receipt. RR No. 18-2013 allows service of PAN, FLD/FAN, and FDDA by personal service, substituted service, or mail, with specific rules for each mode.

The Supreme Court has also ruled in Mannasoft Technology Corporation v. Commissioner of Internal Revenue that personal delivery of the PAN must be made to the taxpayer or a duly authorized representative, not just to anyone at the premises. The Court explained that the recipient must have enough authority to appreciate the seriousness of the notice and its financial impact. (Supreme Court of the Philippines)

This is especially important for corporations, branches, condominium corporations, schools, clinics, restaurants, and family businesses where documents may be received by guards, receptionists, messengers, accounting clerks, or building staff.

You Have the Right to Check the Audit Authority

Before dealing with the amounts in the PAN, check whether the audit itself was properly authorized. In practice, a BIR audit should be supported by a Letter of Authority or electronic Letter of Authority identifying the taxpayer, taxable year, tax types, and assigned revenue officers.

BIR’s 2026 audit framework under Revenue Memorandum Order No. 001-2026 strengthened audit controls, including the use of electronic Letters of Authority and a general single-instance audit framework where, as a rule, one eLA should cover a taxpayer for a given taxable year and applicable internal revenue tax types, including VAT.

How to Respond to a BIR PAN in the Philippines

1. Record the Exact Date and Manner of Receipt

The first practical step is simple but crucial: write down how, when, and by whom the PAN was received.

Keep a copy or photo of:

The PAN and all annexes;
The envelope, if received by mail;
The receiving copy showing the date stamp;
The name, position, and signature of the person who received it;
Any registry receipt, courier tracking, or BIR service details.

Do not count from the date printed on the PAN. Count from the date of actual valid receipt. Because the PAN reply period is short, treat the 15-day period as urgent and do not assume that extensions will be granted.

2. Confirm Whether the PAN Was Properly Served

Check whether the recipient was authorized.

For an individual taxpayer, the PAN should normally be served on the taxpayer or an authorized representative.

For a corporation or partnership, the safer recipients are officers or representatives with clear authority, such as:

President;
Treasurer;
Corporate secretary;
Authorized accounting or tax officer;
Representative named in a board resolution, secretary’s certificate, or special power of attorney.

If the PAN was received by a guard, receptionist, driver, building admin staff, or unrelated employee, note the defect immediately. This may become important if the case reaches the FLD/FAN or CTA stage.

3. Read the PAN by Issue, Not by Total Amount

Many taxpayers panic because the total amount looks huge. Break it down.

Create an issue matrix like this:

BIR finding	Tax type	BIR basis	Amount proposed	Your response	Documents needed
Alleged undeclared sales	VAT / income tax	Third-party matching	₱___	Timing difference / already declared / non-taxable	Sales invoices, VAT returns, ledgers, contracts
Disallowed expenses	Income tax	Lack of substantiation	₱___	Ordinary and necessary expense, supported	Receipts, invoices, proof of payment, contracts
Expanded withholding tax deficiency	EWT	Non-withholding	₱___	Properly withheld / payee exempt / wrong classification	BIR Form 1601-EQ, 2307s, Alphalist
Input VAT disallowance	VAT	Invoice issue	₱___	Valid VAT invoice / properly attributable	VAT invoices, SLSP, books

This approach prevents a vague reply. The BIR rules require issue-specific factual and legal arguments later at the FLD/FAN protest stage, and the same discipline should be used at the PAN stage. For FLD/FAN protests, RR No. 18-2013 states that failure to state the applicable facts, law, rules, regulations, or jurisprudence may cause issues to be treated as undisputed.

4. Gather Documents That Directly Answer Each Finding

Do not submit a mountain of documents without explanation. The better approach is to match each document to a specific issue.

Common documents include:

Category	Examples
Tax returns	Annual income tax returns, quarterly ITRs, VAT returns, percentage tax returns, withholding tax returns, DST returns
BIR attachments	SLSP, SAWT, MAP, QAP, Alphalist, inventory lists
Accounting records	General ledger, subsidiary ledgers, trial balance, audited financial statements, journals
Sales support	Invoices, official receipts, contracts, delivery receipts, billing statements, collection records
Expense support	Supplier invoices, official receipts, proof of payment, contracts, liquidation reports
Withholding tax support	BIR Forms 2307, 2306, 1601 series, Alphalist, payee details
VAT support	VAT invoices, import entries, input VAT schedules, zero-rated sales documents
Authority documents	SPA, board resolution, secretary’s certificate, tax agent authority
Filing proof	Receiving copy, registry receipt, courier proof, email acknowledgment if accepted by the BIR office

For taxpayers abroad, foreign-issued documents may need proper authentication depending on the document and place of execution. The DFA’s Apostille system is the usual reference point for foreign public documents intended for use in the Philippines. (Apostille Services)

5. Prepare a Clear Written Reply to the PAN

A strong PAN reply is usually organized this way:

Heading and taxpayer details
- Taxpayer name;
- TIN;
- Registered address;
- Taxable year;
- PAN number and date;
- Date of receipt.
Introductory statement
- State that the letter is a reply to the PAN.
- Identify the tax types and taxable period covered.
Preliminary objections, if any
- Improper service;
- Lack of authority of revenue officers;
- Wrong taxable period;
- Prescription;
- Lack of factual or legal basis;
- Issues already settled or previously audited.
Issue-by-issue discussion
- BIR finding;
- Taxpayer’s factual explanation;
- Legal basis;
- Computation;
- Supporting documents.
Requested action
- Cancellation of the proposed assessment;
- Reduction or adjustment of specific items;
- Recognition of documents submitted;
- Correction of computational errors.
List of attachments
- Number each attachment and refer to it in the body of the reply.

Avoid a one-page reply that simply says, “We disagree.” A bare denial rarely helps because the PAN stage is your chance to show the BIR why the proposed assessment is wrong before it becomes final.

6. File the Reply With the Correct BIR Office

File the PAN reply with the office that issued the PAN or the office stated in the notice. Depending on the taxpayer, this may be:

Revenue District Office;
Revenue Regional Office Assessment Division;
Large Taxpayers Service;
National Office division handling the audit.

Bring at least two copies: one for the BIR and one receiving copy for your records. The receiving copy should show the date, office, name or initials of the receiving personnel, and stamp if available.

If filing by registered mail or courier, keep proof of mailing and delivery. If the BIR office allows electronic submission, keep the email trail and any acknowledgment, but a stamped physical receiving copy is still often the most practical proof in a contested assessment.

What Happens After You Reply to the PAN?

After receiving your reply, the BIR may:

Drop or revise some findings;
Ask for clarificatory documents;
Maintain the findings and issue an FLD/FAN;
Issue a revised computation;
Proceed to final assessment if it considers the response insufficient.

If the BIR issues an FLD/FAN, the case becomes more serious. The FLD/FAN must state the facts, law, rules and regulations, or jurisprudence on which the assessment is based; otherwise, the assessment may be void.

From receipt of the FLD/FAN, you have 30 days to file a valid administrative protest. If you miss that deadline, the assessment becomes final, executory, and demandable, and no request for reconsideration or reinvestigation will be granted on an assessment that has already become final.

Request for Reconsideration vs. Request for Reinvestigation

If the case reaches the FLD/FAN stage, the type of protest matters.

Type of protest	Meaning	When used	Supporting documents
Request for reconsideration	Re-evaluation based on existing records	When the documents are already in the BIR file and the dispute is mainly legal or computational	No separate 60-day period under RR No. 18-2013
Request for reinvestigation	Re-evaluation based on newly discovered or additional evidence	When you need to submit new documents or factual proof	Relevant supporting documents must be submitted within 60 days from filing the protest

For requests for reinvestigation, RR No. 18-2013 requires the taxpayer to submit all relevant supporting documents within 60 days from filing the protest, otherwise the assessment becomes final in the sense that the taxpayer is barred from disputing correctness through newly discovered or additional evidence.

If the BIR Denies the Protest or Does Not Act

If the protest is denied in whole or in part, the taxpayer may generally appeal to the Court of Tax Appeals within the required period. The CTA has exclusive appellate jurisdiction over decisions of the Commissioner of Internal Revenue in disputed assessments and over inaction where the Tax Code gives the CIR a specific period to act. (Lawphil)

Under RR No. 18-2013, if the protest is not acted upon within the applicable 180-day period, the taxpayer may either appeal to the CTA within 30 days after the 180-day period expires or await the final decision and appeal within 30 days from receipt of that decision. The regulation emphasizes that these options are mutually exclusive: choosing one bars the other.

Common Mistakes When Responding to a PAN

Ignoring the PAN Because It Is “Not Yet Final”

This is one of the most expensive mistakes. A PAN is preliminary, but ignoring it can lead directly to a final assessment.

Waiting for the BIR to Explain Everything Orally

If the PAN and annexes are unclear, put your objection in writing. Oral discussions are helpful, but they do not replace a written reply filed within the deadline.

Filing a Generic Denial

A reply that says “we disagree with all findings” without documents, computations, or legal basis gives the BIR little reason to revise the assessment.

Failing to Raise Procedural Defects Early

Improper service, wrong address, unauthorized recipient, invalid authority, or lack of factual and legal basis should be documented as early as possible.

Forgetting Undisputed Items

At the FLD/FAN protest stage, issues not disputed may become final, executory, and demandable. RR No. 18-2013 specifically provides that if only some issues are disputed, the assessment attributable to undisputed issues may become final and collectible.

Assuming a Closed Business Cannot Be Audited

Closure of business registration does not automatically erase prior tax liabilities. The BIR may still examine covered taxable periods within the applicable prescriptive periods.

Being Abroad and Missing Deadlines

For OFWs, expats, foreign investors, and nonresident owners with Philippine tax registrations, deadlines can still run if notices are validly served at the registered or known Philippine address. A reliable authorized representative is important for receiving and acting on notices promptly.

Practical Scenarios

Small Business Owner With Alleged Undeclared Sales

A sari-sari store supplier, online seller, clinic, restaurant, or contractor may receive a PAN because BIR third-party data does not match declared sales. The reply should explain timing differences, canceled transactions, VAT-exempt items, non-operating income, or amounts already declared under a different line item.

Corporation With Disallowed Expenses

A company may face disallowance of rentals, professional fees, commissions, repairs, representation expenses, or management fees. The reply should show that the expenses are ordinary, necessary, properly substantiated, connected to business, and supported by withholding tax compliance where required.

Foreign-Owned Philippine Corporation

Foreign shareholders often assume the local accountant is handling all BIR notices. For Philippine corporations, however, the taxpayer is the corporation itself. The company should verify who is authorized to receive BIR notices, who can sign replies, and whether the registered address with the BIR is current.

Individual Professional or Consultant

Doctors, lawyers, engineers, consultants, influencers, freelancers, and real estate brokers commonly receive findings involving undeclared income, unissued receipts, unsupported expenses, or withholding tax mismatches. The reply should reconcile professional fees, BIR Forms 2307, books of accounts, bank deposits, and invoices.

Frequently Asked Questions

Can I protest a BIR PAN?

In common usage, yes, people call it “protesting a PAN.” Technically, you file a reply or response to the PAN within 15 days from receipt. The formal administrative protest is filed later if you receive an FLD/FAN.

How many days do I have to answer a PAN?

You have 15 days from receipt of the PAN to file your reply. RR No. 18-2013 states that failure to respond within this period may cause the taxpayer to be considered in default.

What happens if I do not answer the PAN?

The BIR may issue the Formal Letter of Demand and Final Assessment Notice, which starts the 30-day period for filing a formal administrative protest.

Is the PAN already a final tax bill?

No. A PAN is a proposed assessment. The final demand for payment is the FLD/FAN. However, the PAN is still very important because it is part of the due process requirement and gives you the chance to respond before the assessment becomes final.

What if the PAN was received by a security guard or receptionist?

That may be a serious service issue, especially if the person was not authorized to receive tax assessment notices. The Supreme Court in Mannasoft emphasized that PANs personally served should be received by the taxpayer or duly authorized representative. (Supreme Court of the Philippines)

Should my PAN reply be notarized?

A PAN reply is not typically notarized unless the BIR office specifically requires a sworn statement for a particular document or representation. What matters most is that the reply is signed by the taxpayer or authorized representative and supported by relevant documents.

Can I submit additional documents after filing the PAN reply?

At the PAN stage, the BIR may receive clarificatory documents depending on the audit handling office and timing. Do not rely on this. Submit the strongest complete reply within the 15-day period.

What if I agree with part of the PAN but disagree with the rest?

Separate admitted items from disputed items. Make sure your written reply clearly identifies which findings you dispute and why. At the later FLD/FAN stage, undisputed issues may become final and collectible.

Can the BIR collect immediately after the PAN?

The PAN itself is not the final demand for payment. Collection generally proceeds after a valid final assessment becomes final, executory, and demandable, subject to the taxpayer’s remedies.

Does filing a PAN reply stop interest and penalties?

Not necessarily. Proposed deficiency taxes may continue to include applicable interest and penalties if the BIR maintains the assessment. Under RR No. 21-2018, the legal interest imposable under Section 249 of the Tax Code, as amended, was clarified at 12% based on the then-applicable BSP legal interest rate, subject to change if the BSP prescribes a new rate. (Bir.gov.ph)

Key Takeaways

A BIR PAN is not yet the final assessment, but it is a critical deadline-driven notice.
The correct filing at the PAN stage is a reply or response, usually within 15 days from receipt.
The PAN should state the factual and legal bases of the proposed assessment.
Check service, authority, taxable year, tax type, computations, and supporting documents immediately.
A vague denial is weak; answer each BIR finding with facts, law, computations, and attachments.
If the BIR later issues an FLD/FAN, the formal protest deadline is 30 days from receipt.
Missing the FLD/FAN protest period can make the assessment final, executory, and demandable.
Keep complete proof of filing, receiving copies, attachments, and all communications with the BIR.