NTN vs STRN vs CNIC on Invoices: What Goes Where

Last reviewed: 7 October 2026. General information, not tax advice. Check your own registration details in IRIS or with your tax advisor.

A Pakistani invoice can carry up to three identification numbers, and buyers' accounts teams are strict about them. Put the wrong one in the wrong box and the invoice comes back, or worse, FBR's Digital Invoicing (DI) system rejects it before it reaches the buyer. Here is what each number is and where it goes.

The three numbers in one table

FBR described the STRN as a "thirteen digits" number "issued to every person who is registered for sales tax purpose", and said only that person is authorised to charge sales tax on taxable sales (FBR press release, August 2019). It also warned that showing an NTN is not a substitute for an STRN.

Who may put sales tax on an invoice

Section 23(2) of the Sales Tax Act 1990 says that no person other than a registered person (or one paying retail tax) shall issue a sales tax invoice (FBR text updated to 30 June 2026). So if you have an NTN but no sales tax registration, your invoice must not show sales tax. A freelancer, a small consultant outside the sales tax net, or a shop paying tax through its electricity bill issues an ordinary commercial invoice instead.

The seller box

If you are registered for sales tax, show:

• your registered business name and address, exactly as in your FBR profile;
• your NTN (or, for a sole proprietor, the CNIC that serves as NTN);
• your STRN, if you have a separate one. Under DI the system identifies you by NTN or CNIC, but buyers' accounts teams are used to seeing the STRN, and printing it does no harm.

Section 23(1)(a) requires the "name, address and registration number of the supplier". The Sales Tax Rules already switched from "registration number" to "National Tax Number" for the particulars of debit and credit notes back in 2010 (SRO 610(I)/2010), and the DI API field is literally called sellerNTNCNIC. In practice, the NTN or CNIC is what FBR matches.

If you are not registered for sales tax, show your NTN if you have one (buyers who deduct income tax at source usually ask for it), and do not show an STRN or any sales tax line.

The buyer box

Section 23(1)(b) asks for the "name, address and registration number of the recipient". In practice:

In DI, the buyer is also flagged "Registered" or "Unregistered". The NTN or CNIC is optional only for unregistered buyers. Selling to an unregistered or inactive buyer usually adds 4% further tax under section 3(1A) on taxable goods, so the flag matters for the amount, not just the paperwork.

What FBR Digital Invoicing accepts

PRAL's technical documentation v1.12 sets the formats the system checks:

• Seller: a 7-digit NTN or a 13-digit CNIC, and it must belong to the owner of the token used to post the invoice. If not, you get error 0401.
• Buyer: a 13-digit CNIC, or a 7- or 9-digit NTN. Anything else gives error 0002, "Invalid buyer registration no or NTN".
• No dashes or spaces. Send 1234567, not 123456-7, even if your letterhead prints the dash.
• No self-invoicing. If buyer and seller numbers are the same, the invoice is refused.

The FBR invoice number returned by the system starts with the seller's NTN or CNIC, which is why it is 22 characters long for NTN-based sellers and 28 for CNIC-based ones.

Common mistakes

• Printing an STRN you don't have. Some templates come with an STRN box. If you are not registered for sales tax, delete it, and remove the sales tax line too.
• Using the STRN in the DI seller field. The API expects your NTN or CNIC.
• Typing the NTN with a check digit or dash. Many NTN certificates print 1234567-8. Confirm with your software provider which 7 digits FBR expects for your registration.
• A sole proprietor using a business NTN that doesn't exist. For an individual, the CNIC is the identifier. Use it consistently in IRIS and on invoices.
• Copying a buyer's old details. Registrations get suspended and businesses get new NTNs after incorporation. Check active status on the Active Taxpayers List for regular buyers.

How to check a number

• Your own: log in to IRIS and check your registration profile, or look at your registration certificate.
• A buyer's: search their NTN or CNIC on the Active Taxpayers List for sales tax or income tax. DI software can also look up whether a buyer is registered through FBR's registration-type service.

What is still unclear

Some newer registrants say IRIS identifies them for sales tax purposes by NTN alone, while older registrants hold a separate 13-digit STRN. We have not found an FBR notice that formally retires the separate STRN, so check what your own registration certificate shows and print that.

Related reading

For the full list of particulars on a sales tax invoice, see the sales tax invoice format guide. For error 0401 and its cousins, see FBR Digital Invoicing error codes explained. If you are not registered and just need a clean invoice with your NTN on it, the free invoice generator has fields for both your and your client's tax numbers. If you are registered and not yet posting to FBR, our FBR Digital Invoicing setup service in Islamabad and Rawalpindi can help; we work via PRAL and are not affiliated with FBR.