Many people look for a BIR Certificate of Tax Exemption only after a school, scholarship office, employer, cooperative, bank, donor, or government agency asks for one. The confusing part is that “BIR Certificate of Tax Exemption” can mean different things depending on who is applying: a low-income student, an unemployed applicant, a non-stock non-profit corporation, a cooperative, or another organization claiming a special tax exemption. The requirements are not the same. This guide explains the common types of BIR tax exemption certificates in the Philippines, the documents usually required, where to file, how the process works in practice, and the mistakes that often cause delays.

What Is a BIR Certificate of Tax Exemption?

A BIR Certificate of Tax Exemption, often called a CTE or simply a Certificate of Exemption, is a document issued by the Bureau of Internal Revenue (BIR) confirming that a person or organization is exempt from a specific tax or is treated as tax-exempt for a specific purpose.

It is not a general “free pass” from all taxes. The certificate usually applies only to the type of tax exemption, transaction, program, or legal basis stated in the certificate.

For example:

Applicant or situation	Common document requested	Usual purpose
Student, job applicant, livelihood beneficiary, or person with no/low income	BIR Certificate of Exemption for scholarship, job, or livelihood programs	To prove low or no taxable income
Non-stock, non-profit corporation, foundation, association, religious or charitable organization	Certificate of Tax Exemption under Section 30 of the National Internal Revenue Code	To confirm income tax exemption for qualified activities
Cooperative	BIR Certificate of Tax Exemption for cooperatives, usually using BIR Form No. 1945	To confirm tax incentives under the Cooperative Code
Homeowners’ association, non-stock savings and loan association, retirement benefit plan, or non-stock non-profit educational institution	Special CTE or ruling depending on the governing law or BIR issuance	To support a specific exemption recognized by law
Senior citizen or person with disability buying goods or services	Usually not a BIR CTE	The exemption is generally claimed through the required ID and supporting documents, not through an individual BIR CTE

The BIR’s own Citizen’s Charter recognizes a specific Certificate of Exemption for Scholarship and Job/Livelihood Programs for persons with low income or no income, filed with the Revenue District Office (RDO) having jurisdiction over the applicant’s residence or registration. For organizations, especially non-stock non-profit corporations, the BIR applies a different set of rules under Section 30 of the National Internal Revenue Code and related revenue issuances.

Legal Basis for BIR Tax Exemption Certificates in the Philippines

National Internal Revenue Code: Section 30 organizations

The main legal basis for many organizational tax exemption certificates is Section 30 of the National Internal Revenue Code of 1997, as amended. This section lists certain corporations and associations that may be exempt from income tax, such as charitable institutions, religious organizations, business leagues, chambers of commerce, civic leagues, non-stock non-profit educational institutions, and similar entities.

However, the exemption is not automatic just because an entity is registered with the Securities and Exchange Commission (SEC) as “non-stock” or “non-profit.” The BIR looks at two important tests:

Organizational test – The entity’s Articles of Incorporation and By-laws must show that its primary purpose falls within one of the exempt categories under Section 30.
Operational test – The entity’s actual activities must be devoted to its stated exempt purpose, not to private profit or commercial operations.

The BIR also checks the rule against private inurement. This means the organization’s net income or assets must not benefit private individuals, members, trustees, officers, or founders.

The Supreme Court has repeatedly treated tax exemptions strictly because they are exceptions to the general rule that taxes must be paid. In Commissioner of Internal Revenue v. St. Luke’s Medical Center, Inc., the Court emphasized that an organization claiming exemption must satisfy the legal requirements, and income from activities conducted for profit may still be taxable. (Supreme Court E-Library)

Cooperative Code: tax exemptions for cooperatives

For cooperatives, the legal basis is mainly Republic Act No. 9520, or the Philippine Cooperative Code of 2008, and its implementing tax rules. Cooperatives may enjoy tax exemptions and incentives, but they must comply with both Cooperative Development Authority (CDA) and BIR requirements. (Lawphil)

The BIR uses BIR Form No. 1945, called the Application for Certificate of Tax Exemption for Cooperatives, for original issuance and renewal of cooperative tax exemption certificates.

BIR issuances and practical procedures

Several BIR revenue issuances are especially important:

BIR issuance	Why it matters
RMO No. 38-2019	Clarifies the requirements and procedures for Section 30 non-stock non-profit organizations seeking a Certificate of Tax Exemption
RMC No. 127-2024	Removes the ₱100 certification fee for low-income/no-income Certificate of Exemption applications for scholarship and job/livelihood programs, while retaining the ₱30 documentary stamp tax
RMC No. 38-2025	Clarifies the TIN requirement for cooperative members in cooperative CTE applications
RMC No. 123-2024	Clarifies validity rules and exceptions for certain CTEs, including non-stock non-profit educational institutions, homeowners’ associations, non-stock savings and loan associations, and retirement benefit plans
RMO No. 22-2025	Provides special rules for legitimate labor organizations of seafarers, which no longer need to apply for a CTE under that issuance

These rules matter because BIR frontliners usually rely on the latest Citizen’s Charter, Revenue Memorandum Circulars, and Revenue Memorandum Orders when checking your documents.

BIR Certificate of Exemption Requirements for Low-Income or No-Income Individuals

This is the type commonly needed by:

Students applying for scholarships
Job applicants whose employer or agency asks for proof of low or no income
Beneficiaries of livelihood programs
Individuals who do not file income tax returns because they have no taxable income
Parents or guardians asked to prove low income for a school or government program

The BIR service is officially for persons with low income or no income applying for a Certificate of Exemption for Scholarship and Job/Livelihood Programs.

Required documents for individuals

Requirement	Where to get it	Practical notes
Certification of Low Income or No Income signed by the Barangay Chairman	Barangay Hall of the applicant’s residence	Ask the barangay to state clearly that the applicant is unemployed, has no income, or has low income, depending on the facts
Duly notarized Affidavit of Low Income or No Income	Prepared by the applicant, then notarized by a notary public	The affidavit should match the barangay certification; avoid inconsistent statements
Proof of payment of ₱30 loose Documentary Stamp Tax	BIR/RDO payment facility or authorized payment channel, depending on the RDO’s practice	The ₱100 certification fee has been removed, but the ₱30 DST remains
Special Power of Attorney (SPA), if filed through a representative	Executed by the applicant	The BIR Citizen’s Charter requires the SPA to state the specific transaction and generally be valid for one year
Government-issued IDs of the taxpayer-applicant and representative	Applicant and representative	Bring photocopies and originals for comparison

The BIR’s 2026 Citizen’s Charter lists the barangay certification, notarized affidavit, ₱30 loose documentary stamp tax, and representative documents where applicable. BIR RMC No. 127-2024 removed the previous ₱100 certification fee for this type of application, but retained the ₱30 documentary stamp tax because it is imposed under Section 188 of the National Internal Revenue Code.

Step-by-step process for individuals

Identify the correct RDO. File with the RDO having jurisdiction over your residence or where you are registered as a taxpayer. If you already have a TIN, check which RDO holds your registration.
Secure a barangay certification. Go to your barangay hall and request a certification of low income or no income. Bring a valid ID and any supporting document the barangay may require.
Prepare and notarize your affidavit. The affidavit should state your full name, address, income status, and the purpose for requesting the certificate, such as scholarship, job application, or livelihood program.
Prepare the documentary stamp tax payment. Ask the RDO how it wants the ₱30 loose DST paid or attached. Practices may vary slightly depending on the office.
Submit the documents to the RDO Administrative Section. Bring originals and photocopies. If a representative will file for you, the representative should bring the SPA and IDs.
Answer any verification questions honestly. BIR personnel may ask why you need the certificate, whether you have employment, whether you have a TIN, and whether you previously filed income tax returns.
Claim the certificate once released. If the documents are complete and there are no issues, this is commonly handled within the same day or within a short period. Busy RDOs, incomplete documents, or inconsistencies may cause return trips.

Common mistakes by individual applicants

The most common problems are simple but costly:

The barangay certificate says “indigent,” but the affidavit says “unemployed,” without explaining the applicant’s actual income situation.
The affidavit is not notarized.
The applicant goes to the wrong RDO.
The representative has no SPA.
The applicant forgets to bring valid IDs and photocopies.
The school or agency actually wants a Certificate of No Income Tax Return Filed, not a Certificate of Exemption.

Before going to the BIR, read the exact wording of the school, employer, or agency requirement. Some offices casually say “tax exemption,” but what they really need is proof that the person has no taxable income or no filed income tax return.

BIR Certificate of Tax Exemption Requirements for Non-Stock Non-Profit Organizations

A non-stock non-profit corporation does not become income-tax-exempt merely because it is registered with the SEC. The BIR must still check whether the organization qualifies under Section 30 of the Tax Code and whether its documents and activities support the exemption.

This commonly applies to:

Foundations
Charitable institutions
Religious organizations
Civic leagues
Business leagues and chambers of commerce
Non-profit associations
Social welfare organizations
Certain educational, cultural, or scientific organizations

Required documents for Section 30 CTE applications

Under RMO No. 38-2019, the usual requirements include the following:

Requirement	What the BIR checks
Original application letter for tax exemption ruling	The letter should state the specific paragraph of Section 30 being relied on
Certified true copy of latest Articles of Incorporation and By-laws issued by the SEC	The BIR checks if the entity is non-stock, non-profit, and organized for an exempt purpose
Clauses showing no private inurement	The documents should show that no net income or assets benefit private individuals
Clauses on trustee/officer compensation	The BIR checks whether trustees or officers receive compensation inconsistent with non-profit status
Dissolution clause	Remaining assets upon dissolution should go to a similar qualified organization or the Philippine government
Original certification under oath by an executive officer	This should describe past, present, and proposed activities, income sources, disposition of income, revenues sought to be exempt, and compensation paid to trustees, officers, or executives
Original certification from the RDO where registered	This should indicate the TIN and whether there are pending investigations, audits, assessments, refund claims, collection cases, or judicial appeals
Certified true copies of income tax returns or annual information returns and financial statements for the last three years	The BIR compares actual income and expenses with the claimed exempt purpose

Step-by-step process for non-stock non-profit corporations

Confirm the correct Section 30 category. Do not simply write “non-profit.” Identify whether the organization is claiming exemption as a charitable institution, civic league, religious organization, business league, or another specific category under Section 30.
Review the SEC documents before filing. Many applications are delayed because the Articles of Incorporation or By-laws are too generic or missing key clauses on no private inurement, trustee compensation, and dissolution.
Prepare the sworn certification carefully. This is not a mere formality. The BIR uses it to understand what the organization actually does, where its money comes from, and how income is spent.
Secure the RDO certification. The RDO certification tells the reviewing office whether the organization has pending tax issues.
File the application with the RDO where the corporation is registered. RMO No. 38-2019 provides that the request is filed with the RDO, which pre-evaluates the documents before endorsement to the Revenue Region.
Wait for pre-evaluation and endorsement. If the documents are incomplete, the RDO may return the application. If qualified, the RDO prepares the Certificate of Tax Exemption and memorandum for the Regional Director.
If denied, review the reasons carefully. RMO No. 38-2019 provides for a written denial stating the factual and legal basis. It also recognizes an appeal to the Regional Director within 30 days from receipt of the denial.

What the BIR looks for in real life

For Section 30 organizations, the BIR is not only checking paperwork. It is checking consistency.

For example, a foundation may have a charitable purpose on paper, but the BIR may ask questions if:

Most funds are used for salaries, allowances, or benefits of insiders.
The organization regularly sells goods or services like a commercial business.
Large amounts are paid to trustees, incorporators, related companies, or family members.
The financial statements show income from rentals, investments, or commercial activities.
The Articles of Incorporation do not clearly prohibit private benefit.
The organization has not actually conducted meaningful exempt activities.

Even if an entity receives a CTE, the exemption generally covers income received in furtherance of its exempt purpose. Income from properties or activities conducted for profit may still be taxable.

How long is a Section 30 CTE valid?

Under RMO No. 38-2019, a Certificate of Tax Exemption for qualified Section 30 corporations is generally valid for three years, unless revoked or cancelled. The organization may apply for revalidation for another three years if it continues to qualify.

However, RMC No. 123-2024 clarifies that this three-year validity rule does not apply to certain special categories, such as non-stock non-profit educational institutions covered by RMO No. 44-2016, homeowners’ associations covered by RA No. 9904 and related BIR issuances, non-stock savings and loan associations covered by RA No. 8367, and employees’ retirement benefit plans under RA No. 4917 and related regulations. Their certificates generally remain effective unless revoked or recalled by the BIR for valid grounds. (Bir CDN)

BIR Certificate of Tax Exemption Requirements for Cooperatives

Cooperatives have a separate CTE process. They should not use the same checklist as ordinary non-stock non-profit corporations.

The main form is BIR Form No. 1945, the Application for Certificate of Tax Exemption for Cooperatives. The form must generally be filed in three copies, signed by the president or responsible officer, and submitted to the RDO where the cooperative is registered.

Original issuance requirements for cooperatives

For original issuance, BIR Form No. 1945 lists these common requirements:

Requirement	Notes
Certified true copy of Articles of Cooperation and By-laws	Must be certified by the CDA
Certified true copy of the new Certificate of Registration issued by the CDA	Required under the Philippine Cooperative Code
Current Certificate of Good Standing or Certificate of Good Compliance from the CDA	Must be effective as of the date of application
Photocopy of BIR Certificate of Registration, BIR Form No. 2303	Shows the cooperative’s BIR registration details
Certification under oath listing cooperative members, capital contributions, and TINs	Prepared by an authorized cooperative official

Renewal requirements for cooperatives

For renewal, the common requirements include:

Requirement	Notes
Certified true copy of CDA Certificate of Registration	Confirms continuing cooperative registration
Latest Articles of Cooperation and By-laws certified by CDA	Required if there are amendments or updated documents
Current Certificate of Good Standing or Certificate of Good Compliance from CDA	Must be valid/effective at the time of application
Latest audited financial statements	Must generally be for the immediately preceding year and audited by a BIR-accredited independent CPA

TIN requirement for cooperative members

The BIR requires cooperatives to submit a list of members with their Taxpayer Identification Numbers (TINs). RMC No. 38-2025 clarifies that cooperatives must ensure their members have valid TINs and should submit the list together with the other CTE documents.

However, if a cooperative cannot secure all member TINs for justifiable reasons, the cooperative may submit a sworn affidavit explaining the reasons and undertaking to comply within nine months from issuance of the CTE. The BIR clarified that if the member TIN list is the only lacking requirement, the application should still be processed and the CTE may be issued if the sworn affidavit is submitted.

This is important in practice because many cooperatives, especially rural or community-based cooperatives, have members who do not yet know their TIN or have never registered with the BIR.

Continuing compliance for cooperatives

A cooperative’s CTE is not the end of compliance. Cooperatives may still need to file tax returns and submit required reports even if they are tax-exempt.

BIR RMC No. 6-2024 reminds registered cooperatives, whether taxable or not, to file tax returns and pay tax liabilities through the BIR’s electronic systems when applicable. Cooperatives availing of tax incentives must also submit the required Annual Tax Incentives Report and Annual Benefits Report to the CDA by the applicable deadline.

Failure to comply with CDA and BIR reportorial requirements can result in penalties and even revocation of the BIR-issued CTE.

Special Situations and Exceptions

Non-stock non-profit educational institutions

Non-stock non-profit educational institutions are treated under special rules, not always under the regular RMO No. 38-2019 process. RMO No. 38-2019 expressly excludes non-stock non-profit educational institutions covered by RMO No. 44-2016 from its general processing rules.

If the applicant is a school, college, university, or educational foundation, it should check the specific BIR issuances for educational institutions rather than relying only on the ordinary Section 30 checklist.

Homeowners’ associations

Homeowners’ associations may have tax exemptions under Republic Act No. 9904, also known as the Magna Carta for Homeowners and Homeowners’ Associations, and related BIR issuances. Their CTE validity rules are among the exceptions clarified by RMC No. 123-2024. (Bir CDN)

Legitimate labor organizations of seafarers

Under RMO No. 22-2025, legitimate labor organizations of seafarers covered by RA No. 12021 are not required to apply for a CTE under that issuance. Instead, they must comply with the documentary and filing requirements stated in the BIR rules, such as attaching required certifications to their annual income tax return and remaining subject to post-audit.

Foreign non-profit organizations

Foreign organizations should be careful. A foreign non-stock, non-profit organization operating in the Philippines through a branch may not qualify in the same way as a domestic non-stock, non-profit corporation under Section 30. BIR RMO No. 20-2013 addressed this issue and stated that a branch office of a foreign non-stock, non-profit corporation cannot qualify as a tax-exempt corporation under Section 30. (BIR Web Services)

For foreign NGOs, charities, religious organizations, and foundations, the structure matters. In practice, they often need to review whether they should operate through a Philippine domestic non-stock corporation, a branch, a representative office, a treaty-based arrangement, or another legally recognized structure.

Practical Notes for Filipinos Abroad and Foreigners

If the applicant is outside the Philippines, the BIR will usually require a representative to file or follow up with the RDO. For low-income or no-income individual certificates, the BIR Citizen’s Charter allows filing through a representative with an SPA and valid IDs.

When documents are executed abroad, Philippine government offices commonly require proper notarization and authentication. Depending on the country and the document, this may involve an Apostille under the Apostille Convention or consular authentication through a Philippine Embassy or Consulate. The BIR Citizen’s Charter also refers to consularized or apostilled documents in certain tax-related transactions involving documents executed outside the Philippines.

For practical purposes:

If you are a Filipino abroad asking a relative to file with the BIR, prepare an SPA early.
If the SPA is signed abroad, ask the RDO whether it requires apostille or consular authentication.
Send clear copies of your passport or government-issued ID.
Make sure the representative knows your TIN, RDO, Philippine address, and exact purpose of the certificate.
If a foreign organization is applying, review the Philippine entity structure before preparing the CTE application.

Common Reasons BIR CTE Applications Are Delayed or Denied

1. Filing with the wrong RDO

The correct RDO depends on the applicant. Individuals usually file where they reside or where they are registered. Corporations and cooperatives file with the RDO where the entity is registered. Going to the wrong RDO often results in wasted time.

2. Incomplete or uncertified documents

For organizations, the BIR usually requires certified true copies, sworn certifications, and official documents from the SEC, CDA, or RDO. Ordinary photocopies may not be accepted.

3. Missing no-inurement clauses

For non-stock non-profit corporations, the BIR closely reviews whether the Articles of Incorporation and By-laws prohibit private benefit. Missing or weak clauses on no private inurement, trustee compensation, and dissolution can delay or weaken the application.

4. Actual operations do not match the exempt purpose

A corporation may look non-profit on paper but operate like a commercial business. The BIR may question the exemption if most revenue comes from business activities or if funds benefit insiders.

5. Financial statements show taxable income sources

Rental income, investment income, interest income, and income from commercial services may raise questions. The BIR’s position is that exemption does not automatically cover income from property or profit-making activities.

6. Pending tax cases or non-filing

For Section 30 applications, the BIR requires an RDO certification stating whether there are pending investigations, audits, assessments, protests, refund claims, collection cases, or judicial appeals. A pending issue may slow down the application.

7. Expired CDA documents for cooperatives

For cooperatives, the CDA Certificate of Good Standing, Certificate of Good Compliance, or Certificate of Compliance must be current and effective when filed. If the CDA document is expired, the RDO may not process the application.

8. Confusing a CTE with other BIR certificates

Some applicants request the wrong document. A school or employer may ask for “tax exemption,” but the actual requirement may be:

Certificate of No Income Tax Return Filed
Certificate of Registration, BIR Form No. 2303
Taxpayer Identification Number verification
Certificate Authorizing Registration for a property transaction
BIR ruling for a specific transaction
Cooperative CTE
Section 30 CTE

Always match the requested certificate with the purpose.

Estimated Timelines and Fees

Timelines vary by applicant type, RDO workload, and completeness of documents.

Application type	Typical practical timeline	Government fees commonly involved
Low-income/no-income individual certificate for scholarship or job/livelihood	Often same day or within a short period if complete; allow at least one working day	₱30 loose documentary stamp tax; ₱100 certification fee removed under RMC No. 127-2024
Section 30 non-stock non-profit CTE	Several weeks to a few months, depending on document quality, RDO review, and Regional Office action	Filing fees may vary depending on related certifications or documentary stamp tax requirements
Cooperative CTE	Several weeks, depending on CDA documents, member TIN list, and RDO processing	Depends on required documents, certifications, notarization, and BIR processing requirements
Special CTEs or rulings	Varies widely	Depends on the governing law, transaction, and BIR issuance

The biggest factor is not always the official processing time. In real life, delay usually comes from incomplete documents, inconsistent statements, expired certifications, missing sworn statements, or unresolved BIR registration issues.

Frequently Asked Questions

What are the requirements for a BIR Certificate of Tax Exemption for scholarship?

For a low-income or no-income individual applying for a scholarship-related Certificate of Exemption, the usual requirements are a barangay certification of low income or no income, a notarized affidavit of low income or no income, proof of payment of the ₱30 loose documentary stamp tax, and valid IDs. If a representative will file, an SPA and IDs of both the applicant and representative are required.

How much is the BIR Certificate of Exemption in 2026?

For the BIR Certificate of Exemption for scholarship and job/livelihood programs, the ₱100 certification fee has been removed under RMC No. 127-2024. The ₱30 loose documentary stamp tax remains.

Which BIR RDO should I go to for a Certificate of Exemption?

For low-income or no-income individuals, go to the RDO having jurisdiction over your residence or where you are registered. For corporations and cooperatives, file with the RDO where the entity is registered.

Do I need a TIN to get a BIR Certificate of Tax Exemption?

It depends on the type of certificate. Individual applicants may be asked about their TIN or BIR registration status. Organizations and cooperatives are expected to have BIR registration details. Cooperatives must submit member information with TINs, subject to the clarification and temporary compliance rules under RMC No. 38-2025.

Is a BIR Certificate of Tax Exemption the same as a Certificate of No ITR?

No. A Certificate of Tax Exemption or Certificate of Exemption confirms a specific exemption or low/no income status for a stated purpose. A Certificate of No Income Tax Return Filed is different: it usually certifies that no income tax return is on file for a taxpayer or period. Schools, employers, embassies, and agencies sometimes use loose wording, so check the exact requirement before filing.

Does SEC registration as a non-stock non-profit automatically make an organization tax-exempt?

No. SEC registration is only one part of the analysis. The BIR still checks whether the organization qualifies under Section 30 of the Tax Code, whether its purposes and documents meet the organizational test, whether its actual activities meet the operational test, and whether there is no private inurement.

How long is a BIR CTE valid for non-stock non-profit organizations?

For many Section 30 organizations covered by RMO No. 38-2019, the CTE is generally valid for three years unless revoked or cancelled. The organization may apply for revalidation if it still qualifies. Some special entities, such as certain educational institutions, homeowners’ associations, non-stock savings and loan associations, and retirement benefit plans, have different validity treatment under RMC No. 123-2024.

Does a BIR CTE exempt a non-profit from VAT and withholding tax?

Not automatically. For Section 30 organizations, the income tax exemption generally applies only to income received in furtherance of the exempt purpose. The organization may still have withholding tax obligations, and purchases may still be subject to VAT depending on the transaction.

What are the BIR CTE requirements for cooperatives?

For original issuance, cooperatives generally need BIR Form No. 1945, certified true copies of CDA-approved Articles of Cooperation and By-laws, CDA Certificate of Registration, current CDA Certificate of Good Standing or Certificate of Good Compliance, photocopy of BIR Form No. 2303, and a sworn member list with capital contributions and TINs. Renewal requires updated CDA documents and audited financial statements, among others.

Can the BIR deny a Certificate of Tax Exemption application?

Yes. For Section 30 applications, the BIR may deny the application if the organization does not meet the legal requirements or fails to submit complete documents. RMO No. 38-2019 provides that the denial should state the factual and legal basis, and the applicant may appeal to the Regional Director within 30 days from receipt.

Key Takeaways

A BIR Certificate of Tax Exemption is not one single document. The requirements depend on whether the applicant is an individual, non-stock non-profit corporation, cooperative, or special entity.
For low-income or no-income individuals applying for scholarship or job/livelihood purposes, the core requirements are a barangay certification, notarized affidavit, ₱30 loose documentary stamp tax, and representative documents if applicable.
The ₱100 certification fee for low-income/no-income Certificate of Exemption applications has been removed, but the ₱30 documentary stamp tax remains.
SEC registration as a non-stock non-profit corporation does not automatically create income tax exemption. The BIR still applies the organizational test, operational test, and no-inurement rule.
Section 30 organizations should prepare strong SEC documents, sworn activity certifications, financial statements, and RDO certifications before filing.
Cooperatives use BIR Form No. 1945 and must coordinate both CDA and BIR requirements, including the member TIN list rules clarified by RMC No. 38-2025.
A CTE may be revoked or denied if the applicant’s documents, actual operations, or compliance history do not support the claimed exemption.
The most common causes of delay are wrong RDO filing, incomplete documents, expired certifications, inconsistent affidavits, missing notarization, and confusion over which BIR certificate is actually required.