What CAS registration is
A Computerized Accounting System (CAS) is software used to keep books of accounts and print invoices. Registering it with BIR gives you a Permit to Use (PTU) or, under the newer process, an Acknowledgement Certificate (AC). Invoices printed from a registered CAS carry its details at the bottom: the PTU or AC number, the series range and the date issued (RR 7-2024).
| CAS (PTU / AC) | PTI | EIS Certificate | PTT | |
|---|---|---|---|---|
| For | Computerized books and system-printed invoices | Issuing e-invoices | Proving your system works with BIR | Sending sales data to BIR |
| From | BIR, for the system | Your RDO or LTO | BIR’s EIS certification portal | BIR, when it directs you |
| When | Before using the system | Before your first e-invoice | Within 6 months of the PTI | Only when BIR calls for it |
| Shows on | The invoice footer | Your records | Your records | Your records |
| Replaces the others? | No | No | No | No |
Two different questions
RMC 98-2026 (II.7) is explicit: the PTI is separate from a CAS's PTU or AC, and a CAS permit does not by itself authorise e-invoicing. So a business with a registered CAS still needs a PTI. And a business that issues invoices from software is covered by the e-invoicing rule whether or not it has a CAS permit (Section III).
When your system changes
- CAS: RR 11-2024 treats a change in how a CAS issues invoices as a major enhancement that needs a new Acknowledgement Certificate.
- PTI: it names your e-invoicing software; a change of system, or of its identity, needs a new or amended PTI (RMC 98-2026 IV.12).
Do you need CAS registration?
It depends on how you keep your books and print your invoices, and the rules have changed over the years. This is a question for your accountant or RDO: tell them which software you use for invoices and which for your books.
How PrimerLedger helps
PrimerLedger keeps your PTU or Acknowledgement Certificate details in Settings and prints them in the invoice footer, and its BIR connection page tracks your PTI and EIS Certificate separately, with reminders. See also PTU, PTI, EIS Certificate, PTT: which permit do you need?
Official sources
- RR No. 11-2024 Amends the invoicing rules: changing how a CAS prints invoices is a major enhancement that needs a new Acknowledgement Certificate, and it restates the penalty for failing to issue invoices (Tax Code Sec. 264).
- RR No. 7-2024 (digest) The invoicing rules under the Ease of Paying Taxes Act: "Invoice" replaces the official receipt, what every invoice must show (TIN line with branch code, VAT breakdown, buyer details), and the CAS footer.
- RMC No. 98-2026 The e-invoicing guidelines: who is covered, what makes a valid e-invoice, no editing after issue (credit notes instead), outages, the PTI, the EIS Certificate within six months, and the PTT only when BIR directs.
All in one place: official BIR documents on e-invoicing. Guidance in plain words, not tax advice: your accountant or RDO confirms it for your business.