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BIR CAS Registration Philippines: Requirements, Eligibility and Process

Updated on: Aug 13th, 2026

12 min read

BIR CAS registration in the Philippines is the process of registering a computerized accounting system with the Bureau of Internal Revenue and obtaining an Acknowledgement Certificate. The CAS certificate replaced the old Permit to Use in 2021. Philippines businesses need it before being certified on the BIR's Electronic Invoicing System (EIS) from 31 December 2026.

Key Takeaways
CAS registration is mandatory for generating invoices or maintaining books of accounts in the Philippines using a computerized system.
You no longer get a BIR Permit to Use CAS. New CAS registrants receive an Acknowledgement Certificate (AC), but existing PTUs stay valid.
Once your documents are complete, the AC is issued within three working days.
CAS registration and EIS certification are separate steps. You need the AC first, then EIS certification and a Permit to Transmit.
You’ll face penalties under the NIRC, and the EIS will reject your e-invoices if the system is not registered.

What Is a Computerized Accounting System (CAS)?

A computerized accounting system (CAS) is any integrated software used to record business transactions and produce financial records electronically. In BIR terms, it covers the invoicing engine and its components: Computerized Books of Accounts, the Electronic Storage System, middleware, and similar tools. The BIR refers to all of this as the "System."

A registered CAS must generate structured invoice data that can be extracted and transmitted to the BIR. It also needs a tamper-evident audit trail, sequential serial numbers, role-based access, and 10-year retention. A system that only produces a PDF or a scanned copy does not qualify under RR No. 11-2025.

Who Needs to Register a CAS with the BIR?

Any Philippines taxpayer that intends to use a computerized system to issue invoices or keep books of accounts must register it before use. The EIS mandate runs on a Stage 1 and Stage 2 rollout. In practice, that means:

Large Taxpayers and those under the Large Taxpayers Service (LTS) in stage 1.
E-commerce firms, online marketplaces and digital service providers, regardless of size in stage 1.
Exporters of goods and services under Sections 106 and 108, even when zero-rated in stage 2.
Any business already running CAS, CBA or accredited invoicing software in stage 1.
Corporates with large gross sales that fall within the expanded e-invoicing scope in stage 1.

The working threshold of gross sales above PHP 1 billion pulls a taxpayer into the first wave. Micro taxpayers are exempt by law, but may adopt voluntarily. Thresholds change, so confirm your coverage against the current BIR issuance.

Documents Required for BIR CAS Registration

The BIR requires one complete documentation pack. If any item is missing, it is returned and the processing clock restarts. The core BIR CAS requirements are:

Document	Description
Notarised Sworn Statement (Either Annex C - Sworn Statement or Annex E - Joint Sworn Statement)	Declares the System will be used and meets BIR standards; lists modules and version
System/company profile (Summary of System Description, Invoice/Document Description, Forms/Records and Reports Specification (Annex C-1))	Cloud vs on-premise architecture and modules in scope
Sample print-outs	Principal and supplementary invoices showing all BIR-mandatory fields
List of system-generated reports	With sample layouts
Facsimile of books of accounts	General ledger, sales journal, and so on
BIR Form 2303	Certificate of BIR Registration of the taxpayer
Annex B requirements matrix	Maps each BIR rule to a system feature. The BIR examines this item most closely
User / technical manual	Vendor systems need a vendor authorisation letter
Audit-trail design and retention plan	10-year record retention

Under RMO No. 9-2021 and RMC No. 5-2021, the old BIR Form 1900 and the pre-use system demonstration are no longer required.

How to Register CAS with the BIR: Step-by-Step Process

Step 1. Prepare the complete 9-item documentary pack, including the Annex B compliance matrix. It usually takes the longest.

Step 2. Submit the pack to the RDO or Large Taxpayers Office where your head office is registered. You can file manually or electronically through ORUS (Online Registration and Update System).

Step 3. The receiving officer checks for completeness. If anything is missing, the pack is returned, and you re-file.

Step 4. The BIR issues the Acknowledgement Certificate within three working days of receiving complete documents.

Step 5. Register your books and invoice serial ranges, then print the AC control number on every system-generated invoice.

Step 6. The BIR may review the system during a later audit. Non-conformity can lead to revocation of the AC.

Each TIN and branch code files its own AC. If one branch is in scope, the head office and every branch must comply. Plan per-RDO filings for multi-entity rollouts.

BIR CAS Registration Timeline

Stage	Who	Typical duration
Prepare 9-item documentary pack	Taxpayer + vendor	2 to 4 weeks
Submit to RDO / LT Office	Taxpayer	Day 0
Completeness check	BIR	Same day to 1 working day
Issuance of AC	BIR	Within 3 working days of complete docs
Register books and serial ranges	Taxpayer	AC + 1 day
Post-evaluation (during audit)	BIR	Open-ended

Most of the elapsed time is document preparation, not BIR processing. Once a complete pack is submitted, the AC follows within three working days.

Frequently Asked Questions

Is BIR CAS registration mandatory?

Yes. Any taxpayer using a computerized system to issue invoices or keep books must register it before use and hold a valid Acknowledgement Certificate.

Can I modify my CAS after registration?

It depends on the change. A major change, such as a new module affecting books or invoices, a database engine swap, or an on-premise to cloud migration, requires a fresh AC before go-live. A minor change like a bug fix or report formatting is conveyed in a written notification to the RDO/LT Office stating the specific change.

How long does BIR CAS registration take?

The AC is issued within three working days of a complete pack. Plan 2 to 4 weeks in total, because most of the effort goes into preparing the documents, especially Annex B.

Is CAS registration the same as EIS e-invoicing certification?

No. Computerized accounting system registration gives you the AC for your invoicing system. EIS certification is a separate, later step that certifies your ability to transmit sales data and results in a Permit to Transmit. The AC is a prerequisite.

What are the penalties for using an unregistered CAS?

Using an unregistered system, or transmitting without a valid AC, carries NIRC penalties including fines and compromise penalties. The BIR can revoke the AC, and the EIS will reject any e-invoices from a system without one.

What is the difference between BIR CAS registration and BIR EIS certification?

CAS registration BIR covers the system that generates invoices and produces the AC, issued by your RDO. EIS certification covers the system that transmits invoice data and produces the Permit to Transmit, issued after BIR sandbox testing. You need both, the AC first, then EIS certification.

About the Author

Annapoorna

Manager - Content

I preach the words, “Learning never exhausts the mind.” An aspiring CA and a passionate content writer having 8+ years of hands-on experience in deciphering jargon in Indian GST, Income Tax, off late also into the much larger global compliance ecosystem spanning SEA, GCC, USA and EU. I love curating content in various forms to the interest of tax professionals, and enterprises, both big and small. While not writing, you can catch me singing Shāstriya Sangeetha and tuning my violin ;). Read more

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