Your sales tax return and Annex-C, now that invoices go to FBR

Answer first. FBR's monthly sales tax return has three dates. Your sales data in Annex-C is due by the 10th of the next month, the tax by the 15th, and the return itself by the 18th. Since digital invoicing, you no longer type Annex-C: IRIS fills it from the e-invoices you sent to FBR, and you check and submit it. So the real work now is making sure every sale in your books reached FBR, and every invoice FBR holds is right, before the 10th. A late return now costs Rs 50,000.

The three dates: the 10th, the 15th and the 18th

Sales tax is filed every month, for the month just gone. Each date falls in the following month:

So for October 2026, Annex-C is due by 10 November, the tax by 15 November and the return by 18 November. FBR's own due dates page says the same. A few sectors, such as power and gas companies, CNG stations and brick kilns, have their own dates.

What the return holds

The return form is STR-7, the Sales Tax and Federal Excise Return. Most of it is a set of annexes, each holding one kind of data. These are the ones most businesses meet:

The rest of the return adds up your output tax, your input tax and what you owe, then takes your payment details. Everything starts with Annex-C.

How e-invoices fill Annex-C

The Sales Tax Rules now say it in one line: Annex-C "shall be auto-filled from the electronic invoices issued by the integrated person". In IRIS you open Annex-C, press Load Invoices, and the invoices FBR holds for that month appear. You check them and submit. FBR's own FAQ puts the other side just as plainly: every sale you report in Annex-C needs a digital invoice.

Two timing rules decide what lands in the month:

• 72 hours, or month end. An invoice moves into your return 72 hours after it is posted, or at month end, whichever comes first. Until then, you can cancel or edit it yourself in FBR's portal if it was a genuine mistake. After that, a change needs the Commissioner's approval.
• Returns and price cuts are never mistakes. They need a debit or credit note against the original invoice, within 180 days of the sale. Notes go in Annex-I, in the month you issue them.

Our post on cancelling or editing an FBR invoice covers both in detail.

Your Annex-C is your buyers' input tax

Annex-C isn't only your business. The moment you submit it, its data appears in each buyer's "Purchase Data" in IRIS. Your buyers load it into their own Annex-A to claim input tax on what they bought from you.

That has three effects your customers feel:

• No Annex-C, no input tax. A buyer can't claim input tax on a sale you didn't declare.
• Their return waits for yours. A buyer's return stays provisional until you file. If you haven't filed by the last day of the month your return was due, IRIS deletes your invoices from their return. It takes away the input tax and works out what they owe.
• Mismatches cost them 20%. Since 1 July 2026, FBR's system matches each buyer's input tax against what the supplier declared. Where it doesn't match, the buyer pays a penalty of 20% of the unmatched amount, after a notice and a hearing. That comes on top of paying back the credit, with default surcharge.

So a late or messy Annex-C doesn't stay with you. It lands on your customers, and the good ones notice. See all of the 2026 changes in our Finance Act 2026 penalties post.

Where gaps come from

A gap is any difference between the sales in your books and the e-invoices FBR holds. These are the usual causes:

The first and last rows got more expensive in September 2026. Rule 150XD(2), added by SRO 1666 on 29 September 2026, covers two cases: a sale made without an FBR-numbered invoice, and an FBR-numbered invoice missing from Annex-C or the return, unless it was cancelled through the legal route. In both, an officer works out the tax and recovers it, and penal action can follow.

FBR also checks automatically now. Since SRO 1655 of 25 September 2026, its system cross-matches returns with other data and can send an advance intimation in IRIS when it finds a discrepancy. You get at least seven days to answer. Our post on advance intimations in IRIS explains how to reply.

A month-end routine that keeps Annex-C clean

1. Every day: clear rejected invoices. Fix the cause and send them again while the sale is fresh.
2. Every week: match your sales register against the invoices FBR accepted. Any sale without an FBR number gets sent.
3. The last three days of the month: fix mistakes on the same day. The 72-hour window closes at month end.
4. By the 10th: load Annex-C in IRIS, check its total against your sales register, and submit Annex-C and Annex-I.
5. By the 15th: pay the tax.
6. By the 18th: file the return.

eInvoicePro, our FBR digital invoicing software, makes the first three steps quick. Every invoice FBR accepted sits in one list with its FBR number, ready to print or download. Rejected invoices sit in another, with FBR's reason next to each, ready to send again. The dashboard shows sent, pending and failed invoices for the month at a glance, so the month-end check is a comparison of two lists, not a hunt.

Filing the return in IRIS

Log in to IRIS, then:

1. Open Declaration and start the Sales Tax and Federal Excise Return for the month.
2. In Annex-C, press Load Invoices, check the list and submit it.
3. In Annex-A, load your purchases and claim the input tax on them.
4. Fill any other annex that applies to you, such as Annex-I for notes or Annex-J for production.
5. Let IRIS work out the tax, then add the payment details of the tax you paid.
6. Enter your PIN and submit. A submitted return can't be edited, only revised.

Late, wrong or revised returns

The Finance Act 2026 raised the fines from 1 July 2026:

Late tax also carries default surcharge, at 12% a year or KIBOR plus 3%, whichever is higher, counted from the 16th.

More time. You can ask your Commissioner, before the due date, for up to 15 more days to file. It doesn't move the date to pay. FBR also extends dates for everyone at times. It moved the August 2026 return to 25 September 2026, for those who had paid their tax on time.

Fixing a filed return. You can revise a return within 60 days without approval if you are paying more tax or claiming less refund. Up to 120 days, a revision to correct a mistake needs the Commissioner's approval. Revise on your own, with the tax and default surcharge, before an audit notice arrives, and no penalty applies. A return more than six months late can only be filed with the Commissioner's approval.

FAQs

What is the last date for the FBR sales tax return? The 18th of the month after the tax period. The tax must be paid by the 15th, and Annex-C by the 10th. For October 2026 sales, that is 10, 15 and 18 November.

What is Annexure-C of the sales tax return? Annexure-C, or Annex-C, lists your sales invoices inside Pakistan for the month. For businesses on FBR digital invoicing it is filled automatically from the e-invoices you sent to FBR, and your buyers' input tax claims are loaded from it.

Do I still fill Annex-C by hand? No. In IRIS you press Load Invoices in Annex-C and the e-invoices FBR holds for the month appear. You check them and submit. A sale that never reached FBR as an e-invoice won't be there, which is why every sale needs one.

What does it mean when sales invoices are not linked with Annex-C? It means the sales in your return and the invoices in Annex-C don't line up for that month. Load the invoices in Annex-C again for the right tax period, check that every sale has an FBR invoice, then submit Annex-C before filing the return.

What is the penalty for a late sales tax return? From 1 July 2026, Rs 50,000. If you file within 10 days of the due date, it is Rs 2,000 a day instead. Paying the tax late costs Rs 50,000 or 5% of the tax, whichever is higher, plus default surcharge.

Has FBR extended the sales tax return date? FBR announces each extension separately, usually only for filing, and only for those who paid on time. The August 2026 return, for example, was extended to 25 September 2026. You can also ask your Commissioner for up to 15 more days before the due date.

Can I revise my sales tax return? Yes. Within 60 days you can revise without approval if you are paying more tax or claiming less refund. Up to 120 days, a revision needs the Commissioner's approval. A voluntary revision with the tax and surcharge, before an audit notice, carries no penalty.

Related reading: how to cancel or edit an FBR invoice, the Finance Act 2026 penalties, what an STRN is and how to check one and FBR's faceless audit.