How Digital Invoicing Feeds Your Sales Tax Return (Annexure-C) in 2026
When you post invoices through FBR Digital Invoicing, the same data flows into your monthly sales tax return — auto-populating Annexure-C so you no longer re-key every sale. Here is how the link works, what still needs checking, and the monthly filing dates.
Annexure-C: the sales side of your monthly return
Every sales tax registered person files a monthly sales tax return, and Annexure-C is the part that lists all outward supplies — each sales invoice, debit note and credit note issued during the tax period. Traditionally businesses typed this data into IRIS by hand, which is slow and error-prone.
Digital Invoicing changes that. Because every invoice is already transmitted to FBR in real time, the sales data needed for Annexure-C is captured at the moment of sale rather than reconstructed at month-end.
How auto-population works
Invoices you post through the Digital Invoicing system are stored against your registration in FBR's records. When you create your monthly sales tax return in IRIS, the invoices already in the system — including invoices your suppliers issued to you — are loaded into the relevant annexure automatically, so Annexure-C is pre-filled from your digital invoices instead of manual entry.
This is one of the biggest practical benefits of e-invoicing: the return becomes a review-and-confirm exercise rather than a re-typing exercise, and the sales figures in your return match the invoices FBR already holds.
What you still need to check
Auto-population is only as accurate as the invoices behind it. If an invoice was posted with the wrong sale type, HS Code, tax rate or buyer, that error carries into Annexure-C — so it pays to validate and correct invoices during the 72-hour window rather than at return time.
You should still reconcile the auto-loaded annexure against your own records before submitting, confirm any purchase-side data, and make sure nothing issued outside the digital system is missing. Digital invoicing removes the typing, not the responsibility to file a correct return.
The monthly sales tax filing dates
The monthly cycle is unchanged: as a general rule Annexure-C (sales) is submitted by the 10th of the following month, payment is due by the 15th, and the return itself by the 18th. Always confirm the current dates and any extensions on the FBR portal, as they can change.
By posting cleanly through Digi Invoice all month, your Annexure-C data is ready when the return opens — validated, QR-stamped and consistent with what FBR already has on record.