A BIR Preliminary Assessment Notice (PAN) can feel alarming because it usually lists proposed deficiency taxes, surcharge, interest, and compromise penalties. But a PAN is not yet the final BIR assessment. It is the BIR’s written notice that, after audit or review, it believes there is a sufficient basis to assess additional tax. The most important thing to know is this: you generally have 15 days from receipt of the PAN to file a written reply explaining why you disagree, with documents that support your position. Missing this stage does not always end the case, but it usually allows the BIR to move forward to the Formal Letter of Demand and Final Assessment Notice, where the deadlines become even more dangerous.

What Is a Preliminary Assessment Notice?

A Preliminary Assessment Notice, commonly called a PAN, is a written notice from the Bureau of Internal Revenue (BIR) informing a taxpayer of a proposed deficiency tax assessment.

It normally comes after earlier audit steps, such as:

a Letter of Authority (LOA) authorizing named revenue officers to examine the taxpayer’s books;
requests for accounting records, invoices, receipts, contracts, schedules, and reconciliations;
a Notice of Discrepancy (NOD) or similar pre-assessment communication where the taxpayer is asked to explain differences found by the BIR; and
discussions with the assigned Revenue Officer or Assessment Division.

Under Revenue Regulations No. 18-2013, if the BIR determines after review and evaluation that there is sufficient basis to assess deficiency taxes, it must issue a PAN showing in detail the facts, law, rules, regulations, or jurisprudence on which the proposed assessment is based. The taxpayer then has 15 days from receipt to respond.

In ordinary terms, the PAN is the BIR saying:

“Based on our audit, we think you underpaid taxes. Here are our proposed findings. Explain why we should not issue a final assessment.”

Is a PAN the Same as a Final Assessment Notice?

No. This distinction matters because many taxpayers panic and treat the PAN as if collection is already imminent.

Document	What it means	Deadline	Main consequence
Notice of Discrepancy (NOD)	BIR tells you there are discrepancies and gives you a chance to explain before a PAN	Usually short; discussion period may be limited	Helps prevent or reduce a PAN
Preliminary Assessment Notice (PAN)	BIR proposes deficiency taxes but has not yet issued the final assessment	15 days from receipt to reply	If unresolved, BIR may issue FLD/FAN
Formal Letter of Demand / Final Assessment Notice (FLD/FAN)	BIR makes a formal demand for payment	30 days from receipt to file administrative protest	If not validly protested, assessment becomes final, executory, and demandable
Final Decision on Disputed Assessment (FDDA)	BIR decides the taxpayer’s protest against the FLD/FAN	Usually 30 days from receipt to appeal to the Court of Tax Appeals	If not appealed on time, assessment may become final

Strictly speaking, the “protest” under Section 228 of the National Internal Revenue Code applies to the final assessment or FLD/FAN. The response to a PAN is usually called a reply to PAN, response to PAN, or PAN protest in everyday practice. Still, because many taxpayers search for “how to protest a BIR PAN,” this article uses “protest” in the practical sense of disputing the proposed assessment at the PAN stage.

Legal Basis: Your Rights When You Receive a PAN

The main legal basis is Section 228 of the National Internal Revenue Code of 1997, as amended by Republic Act No. 8424, the Tax Reform Act of 1997. It requires that taxpayers be informed in writing of the law and facts on which an assessment is made; otherwise, the assessment is void. (Lawphil)

The detailed assessment procedure is found in Revenue Regulations No. 12-99, as amended by Revenue Regulations No. 18-2013, and later regulations affecting the pre-assessment process.

Your key rights include:

The right to written notice of the facts and law. The PAN should not be a bare table of amounts. It should explain the factual and legal basis of the proposed deficiency taxes.
The right to be given 15 days to respond to the PAN. The BIR’s own rules require that the taxpayer be given this period before the BIR proceeds to the FLD/FAN stage.
The right to proper service. The Supreme Court has emphasized that service of assessment notices must be made on the taxpayer or a duly authorized representative. In a 2023 decision involving Mannasoft Technology Corporation, the Court ruled that the PAN and similar notices must be received only by the taxpayer or authorized representatives, not just any employee or security guard. (Supreme Court of the Philippines)
The right to due process. In Commissioner of Internal Revenue v. Metro Star Superama, Inc., the Supreme Court held that failure to send or prove receipt of the PAN violates due process and may render the assessment void. (Lawphil)
The right to an assessment based on actual legal and factual grounds. In Commissioner of Internal Revenue v. Avon Products Manufacturing, Inc., the Supreme Court stressed that the BIR must meaningfully inform the taxpayer of the bases of the assessment and address the taxpayer’s submissions, instead of simply ignoring the taxpayer’s explanations. (Lawphil)

The 15-Day Deadline to Reply to a BIR PAN

The usual rule is simple but strict:

You have 15 days from the date you received the PAN to file your written reply.

Under RR No. 18-2013, if the taxpayer fails to respond within 15 days from receipt of the PAN, the taxpayer is considered in default, and the BIR may issue the FLD/FAN demanding payment of the deficiency tax plus applicable penalties.

How to Count the 15 Days

For practical purposes:

Start counting from the day after actual receipt of the PAN.
Calendar days are usually counted, not working days.
If the last day falls on a weekend or legal holiday, the deadline may move to the next working day under general procedural rules.
Keep proof of the date of receipt, such as the stamped receiving copy, registry return card, courier proof, email printout if applicable, or BIR transmittal.

The date of receipt is often the first battleground in BIR assessment cases. A taxpayer who cannot prove when the PAN was received may have difficulty showing that the reply was timely.

What to Do Immediately After Receiving a PAN

1. Do not ignore it, even if you think the BIR is wrong

Some taxpayers assume that because the PAN is “preliminary,” they can wait for the final assessment. That is risky.

A strong PAN reply can:

reduce the assessment before it becomes final;
correct misunderstandings in the audit;
preserve factual defenses;
create a paper trail showing that the BIR was informed of your side; and
help later if the case reaches the FLD/FAN, FDDA, or Court of Tax Appeals.

2. Identify exactly what taxes and periods are covered

Check the PAN carefully. It should state the taxable year or period and the tax types involved, such as:

income tax;
value-added tax (VAT);
percentage tax;
expanded withholding tax;
withholding tax on compensation;
final withholding tax;
documentary stamp tax;
excise tax; or
compromise penalties.

Do not assume the BIR’s computation covers only one tax type. Many PANs contain several assessments bundled together.

3. Check who received the PAN

For individuals, check whether the PAN was received personally or by someone clearly authorized.

For corporations, partnerships, and other juridical entities, check whether the recipient was an officer, authorized employee, registered representative, or person with actual authority to receive BIR assessment notices.

This matters because the Supreme Court has recognized that assessment notices should not be served on persons who lack authority to understand the significance of the notice for the taxpayer. (Supreme Court of the Philippines)

4. Review the Letter of Authority

In most BIR audit cases, the audit should be supported by a valid Letter of Authority. The LOA identifies the taxpayer, taxable period, tax types, and revenue officers authorized to conduct the examination.

Check whether:

the LOA covers the same taxable year or period stated in the PAN;
the tax types assessed are within the LOA;
the revenue officers who conducted the audit are named or properly authorized;
the LOA was served on the taxpayer; and
any reassignment of revenue officers was properly authorized.

An invalid or missing LOA can be a serious due process issue because BIR officers generally need authority to examine the taxpayer’s books and recommend assessments.

5. Compare the PAN with your records

The PAN often arises from differences between BIR records and the taxpayer’s filed returns. Common sources include:

sales per VAT returns not matching income tax returns;
purchases claimed without valid invoices;
expenses disallowed for lack of substantiation;
withholding tax not remitted;
alphalist discrepancies;
related-party transactions;
undeclared income based on third-party information;
unsupported input VAT;
timing differences between accounting books and tax returns; and
BIR disallowance of deductions for lack of official receipts, invoices, contracts, or proof of payment.

Prepare a schedule comparing the BIR’s figures with your own books and returns. Do not rely on general statements like “the assessment is wrong.” The reply should show where and why the computation is wrong.

Step-by-Step Guide: How to Protest or Reply to a BIR PAN

Step 1: Calendar the deadline

Write down:

date of receipt;
15th day from receipt;
BIR office that issued the PAN;
name of Revenue Officer or Assessment Division contact person;
tax types and taxable periods involved; and
amount of proposed deficiency tax, surcharge, interest, and penalties.

Set the internal deadline earlier than the actual deadline. In practice, waiting until the last day is risky because receiving windows, signatories, notarization, attachments, and traffic can cause avoidable problems.

Step 2: Request and organize the working papers if needed

If the PAN or Details of Discrepancy is unclear, ask for clarification or copies of schedules used by the BIR. The taxpayer should be able to understand the factual and legal bases of the proposed assessment.

Organize the file by tax type:

Income Tax
VAT or Percentage Tax
Withholding Taxes
Documentary Stamp Tax
Penalties and Interest
Procedural Defenses

This makes the reply easier to read and helps prevent one issue from being treated as undisputed later.

Step 3: Decide your main defenses

Common defenses in a PAN reply include:

the BIR used the wrong tax base;
the BIR counted the same income twice;
the BIR treated non-taxable receipts as taxable income;
the BIR disallowed expenses even though they are ordinary, necessary, substantiated, and properly withheld when required;
the BIR imposed VAT on transactions that are VAT-exempt, zero-rated, or outside the scope of VAT;
input VAT was validly claimed and supported;
withholding tax was already remitted;
the assessment is based on third-party information that is incomplete or incorrectly matched;
the PAN does not state enough facts and law;
the PAN was improperly served;
the audit was conducted by unauthorized officers; or
the right of the BIR to assess has prescribed.

Step 4: Prepare supporting documents

A good PAN reply is evidence-driven. Attach documents that directly answer the BIR’s findings.

Issue	Useful documents
Alleged undeclared sales	Sales journals, VAT returns, income tax returns, audited financial statements, reconciliations, official receipts, invoices
Disallowed expenses	Supplier invoices, official receipts, contracts, purchase orders, proof of payment, withholding tax returns
VAT discrepancies	VAT returns, input VAT schedules, import documents, zero-rating support, sales invoices
Withholding tax findings	BIR Forms 1601 series, alphalists, proof of payment, certificates of tax withheld
Related-party transactions	Contracts, transfer pricing documentation if applicable, board approvals, invoices
Timing differences	Reconciliation schedules, ledgers, journal entries, explanations of accruals or reversals
Service or authority issues	LOA, PAN envelope, registry card, receiving copy, secretary’s certificate, authorization letters

Do not attach a huge pile of documents without explanation. BIR examiners are more likely to understand your position if each attachment is labeled and tied to a specific argument.

Step 5: Draft the PAN reply clearly

The reply should be formal, but it does not need to be written in complicated legal language. It should usually contain:

Heading and taxpayer details Include taxpayer name, TIN, registered address, taxable year, tax type, PAN reference number, and date of receipt.
Statement that the reply is timely filed State when the PAN was received and that the reply is filed within 15 days.
Summary of disputed findings List the tax types, BIR proposed amount, taxpayer’s admitted amount if any, and disputed amount.
Factual explanation Explain what happened in plain language, supported by schedules.
Legal basis Cite the relevant provisions of the Tax Code, revenue regulations, BIR issuances, and court doctrines.
Documentary support Refer to attachments by annex number.
Specific request Ask the BIR to cancel, withdraw, revise, or reduce the proposed assessment.
Reservation of rights State that the taxpayer reserves the right to submit additional explanations and documents if required.

Step 6: File the reply with proof of receipt

File the reply with the BIR office that issued the PAN, usually the Revenue District Office, Regional Assessment Division, Large Taxpayers Service, or other issuing office.

Bring at least:

original signed reply;
duplicate receiving copy;
annexes and schedules;
authorization letter or secretary’s certificate for the representative;
valid IDs; and
proof of authority for the person filing.

Make sure the BIR receiving copy is stamped with:

date received;
time received if possible;
name or initials of receiving officer;
office stamp; and
number of pages or annexes received if the office allows it.

For mailing or courier filing, keep the registry receipt, proof of mailing, tracking record, and complete copy of what was sent.

What Happens After You File the PAN Reply?

After receiving the reply, the BIR may:

accept your explanation and cancel the proposed assessment;
reduce or revise the proposed deficiency tax;
ask for more documents or clarification;
maintain its findings and issue an FLD/FAN; or
issue an FLD/FAN without adequately addressing your reply, which may become a due process issue later.

Under RR No. 18-2013, if the taxpayer responds within 15 days but the BIR still disagrees, the BIR may issue the FLD/FAN within 15 days from filing or submission of the taxpayer’s response.

If the BIR Issues an FLD/FAN After the PAN

The FLD/FAN is the stage where the formal protest deadline applies.

Under RR No. 18-2013, the taxpayer or authorized representative may administratively protest the FLD/FAN within 30 days from receipt by filing either a request for reconsideration or request for reinvestigation. The protest must state the nature of the protest, the date of the assessment notice, and the applicable law, rules, regulations, or jurisprudence relied upon; otherwise, the protest may be considered void and without force and effect.

Request for Reconsideration vs. Request for Reinvestigation

Type of protest	Meaning	When useful	Document rule
Request for Reconsideration	You ask the BIR to re-evaluate based on existing records	Best when documents were already submitted and the issue is legal or computational	The 60-day submission period for new documents generally does not apply
Request for Reinvestigation	You ask the BIR to consider newly discovered or additional evidence	Best when important documents were not previously submitted	Supporting documents must be submitted within 60 days from filing of protest

For reinvestigation, failure to submit relevant supporting documents within 60 days can cause the assessment to become final in the sense that the taxpayer may be barred from disputing it through new or additional evidence.

When a PAN Is Not Required

A PAN is generally required, but Section 228 of the Tax Code and RR No. 18-2013 recognize exceptions. The BIR may issue the FLD/FAN outright without a PAN in specific cases, including:

when the deficiency tax results from a mathematical error appearing on the face of the return;
when there is a discrepancy between tax withheld and tax actually remitted by the withholding agent;
when a taxpayer who claimed a refund or tax credit of excess creditable withholding tax also carried over and applied the same amount to succeeding tax liabilities;
when excise tax due on excisable articles has not been paid; and
when articles bought or imported tax-exempt are later sold, traded, or transferred to non-exempt persons.

If your case does not fall under these exceptions and the BIR skipped the PAN, that may be a major due process defense.

Common Mistakes When Replying to a BIR PAN

Ignoring the PAN because it is “only preliminary”

This is one of the most common mistakes. The PAN stage is often the best chance to correct errors before the assessment becomes harder and more expensive to fight.

Filing a general denial

A reply that merely says “we disagree” is weak. The BIR needs specific explanations, figures, and documents.

Missing some tax issues

If the PAN contains income tax, VAT, and withholding tax findings, answer each one. Do not focus only on the largest amount and leave smaller items unexplained.

Submitting documents without a reconciliation

Documents are useful only if the BIR can connect them to the disputed findings. Always include schedules, summaries, and references to annexes.

Letting unauthorized people receive BIR notices

For companies, receptionists, guards, junior staff, or third-party office personnel may receive notices without understanding their importance. This creates problems in proving deadlines and authority.

Forgetting the FLD/FAN deadline

Even if you filed a strong PAN reply, you must still watch for the FLD/FAN. If it arrives, the 30-day protest period is separate and critical.

Practical Tips for Individuals, Small Businesses, and Foreigners

For self-employed individuals and professionals

Doctors, consultants, freelancers, online sellers, real estate brokers, and other professionals often receive PANs because of mismatches between income tax returns, VAT or percentage tax returns, withholding certificates, and third-party reports.

Useful documents include:

books of accounts;
invoices and receipts;
BIR Form 2307 certificates;
bank records tied to business receipts;
contracts and engagement letters;
proof of withholding tax credits; and
reconciliations between gross receipts and taxable income.

For corporations and partnerships

Companies should immediately involve the finance team, bookkeeper, external accountant, corporate secretary, and responsible officers. The PAN reply should be consistent with the audited financial statements, tax returns, general ledger, and prior submissions to the BIR.

A board resolution or secretary’s certificate may be needed to prove the authority of the representative signing or filing the reply.

For foreigners and foreign-owned Philippine companies

Foreigners doing business in the Philippines, resident foreign nationals, branch offices, and foreign-owned domestic corporations should pay close attention to:

whether the Philippine entity, branch, or individual taxpayer is the proper party assessed;
tax treaty issues, if applicable;
withholding tax on payments to non-residents;
VAT treatment of cross-border services;
documentation for reimbursements and management fees;
apostilled or authenticated foreign documents, if used as evidence; and
whether foreign-language documents need translation.

If supporting documents come from abroad, allow time for notarization, apostille, consular authentication if still required for a particular document, certified translation, and courier delivery. BIR deadlines will not automatically pause just because documents are overseas.

Frequently Asked Questions

Can I protest a BIR PAN?

Yes, in practical terms. The technical term is usually a reply to PAN or response to PAN, not the formal administrative protest under Section 228. The formal protest applies to the FLD/FAN. But when people say “protest a PAN,” they usually mean filing a written reply disputing the proposed deficiency taxes within 15 days from receipt.

How many days do I have to answer a PAN?

You generally have 15 days from receipt of the PAN. If you do not respond within that period, the BIR may consider you in default and proceed to issue the FLD/FAN.

What happens if I do not reply to the PAN?

The BIR may issue a Formal Letter of Demand and Final Assessment Notice. You may still protest the FLD/FAN within 30 days from receipt, but skipping the PAN reply may weaken your position because you lost an early chance to explain the discrepancy and submit documents.

Is the PAN already collectible?

Generally, no. The PAN is a proposed assessment. Collection normally becomes a serious risk after a valid FLD/FAN becomes final, executory, and demandable, or after later stages such as denial of protest and failure to appeal on time.

What if the PAN does not explain the facts and law?

That may be a due process issue. The Tax Code requires taxpayers to be informed in writing of the law and facts on which the assessment is made; otherwise, the assessment may be void. A PAN or later FLD/FAN that merely lists amounts without meaningful factual and legal basis may be vulnerable to challenge.

Can the BIR issue a final assessment before the 15-day PAN period ends?

The BIR should observe the 15-day period. The Supreme Court has recognized that the opportunity to respond to the PAN is part of due process. In CIR v. Yumex Philippines Corporation, the Court emphasized the taxpayer’s 15-day period to respond before issuance of the FLD/FAN. (Lawphil)

What if the PAN was received by a guard, receptionist, or employee who is not authorized?

Improper service can be a serious issue, especially for corporations. The Supreme Court has stated that PANs and similar notices should be served on the taxpayer or a duly authorized representative, because the recipient must have enough authority to understand the importance and consequences of the notice. (Supreme Court of the Philippines)

Should I pay the amount in the PAN immediately?

Payment depends on the facts. If the BIR finding is clearly correct, payment may reduce further interest. If the assessment is wrong, unsupported, prescribed, or procedurally defective, a written reply with evidence may be more appropriate. If only some items are correct, identify and separate admitted items from disputed items.

Can I submit additional documents after filing the PAN reply?

At the PAN stage, the BIR may still receive clarifications or additional documents depending on the audit handling. But do not rely on informal extensions. Submit the strongest possible reply within the 15-day period. At the FLD/FAN protest stage, the rules on requests for reinvestigation and the 60-day document submission period become more formal.

Where do I file the PAN reply?

File it with the BIR office that issued the PAN, such as the Revenue District Office, Regional Assessment Division, Large Taxpayers Service, or other office stated in the notice. Always keep a stamped receiving copy or reliable proof of filing.

Key Takeaways

A BIR PAN is a proposed assessment, not yet the final demand for payment.
The usual deadline to reply is 15 days from receipt.
The reply should be specific, evidence-based, and organized by tax type and issue.
The PAN should state the facts and law supporting the proposed assessment.
Proper service matters; notices should be received by the taxpayer or an authorized representative.
If the BIR later issues an FLD/FAN, the taxpayer has 30 days from receipt to file a formal administrative protest.
Missing the FLD/FAN protest deadline can make the assessment final, executory, and demandable.
Strong documentation, clear reconciliations, and careful deadline tracking are often the difference between a reduced assessment and a costly tax dispute.