How to File a Sales Tax Return in Pakistan (Step by Step)

If your business is registered for sales tax in Pakistan, you must file a return every single month — even in months with no sales. This guide walks through the process on FBR’s IRIS portal, the deadline you cannot miss, and how to keep it painless. (Not registered yet? Start with our guide to sales tax registration in Pakistan.)

When is the sales tax return due?

As a general rule, the monthly sales tax return is filed on the FBR IRIS portal by the 18th of the following month (with tax payment typically deposited by the 15th). Miss it and penalties apply — commonly PKR 10,000 or 5% of the tax due, whichever is higher, plus default surcharge. Filing on time is far cheaper than filing late.

Before you log in: get your data ready

Filing is quick when your records are in order. Gather:

• All sales (output) tax invoices issued to customers for the month
• All purchase (input) tax invoices from registered suppliers
• Details of any exports or zero-rated supplies
• Your STRN and IRIS login credentials

This is where using proper accounting software pays off: your output and input tax are already captured and totalled, so there is nothing to reconstruct by hand at month-end.

Filing your return, step by step

1. Step 1 — Log in to IRIS. Go to the FBR IRIS portal and sign in with your registration number and password.
2. Step 2 — Open the Sales Tax Return. Navigate to Declaration → Sales Tax → Sales Tax Return and select the correct tax period (month and year).
3. Step 3 — Enter output tax. Record your sales to customers and the tax charged (or import/annex it from your records).
4. Step 4 — Enter input tax. Record your purchases from registered suppliers and the tax paid, so you can claim eligible input tax.
5. Step 5 — Let IRIS calculate. The system works out your net tax payable (output tax minus admissible input tax).
6. Step 6 — Pay, then submit. Generate a payment challan (PSID) and pay the amount due, then review the summary and submit the return.

What is a “nil return” — and do I need one?

Yes. If you had no sales in a month, you still must file a nil return. Skipping it because “there was nothing to report” is one of the most common — and easily avoided — reasons businesses rack up penalties and become non-compliant.

Common mistakes to avoid

• Filing late — the deadline is monthly and unforgiving.
• Claiming input tax on invoices from unregistered suppliers or invalid invoices.
• Mismatched figures between your books and the return.
• Forgetting the nil return in a slow month.

How the right software makes filing effortless

Most of the pain in filing comes from assembling the numbers, not the submission itself. When your sales, purchases and tax live in one system:

• Output and input tax are captured automatically as you invoice and buy
• Your figures reconcile with your books, reducing mismatches
• Reports give you return-ready totals in seconds
• With FBR digital invoicing, your sales are already reported in real time

See how Octal Accounts automates sales tax so month-end filing becomes a formality rather than a scramble.

The takeaway

Filing a sales tax return in Pakistan is a fixed monthly rhythm: gather your invoices, enter output and input tax on IRIS, pay, and submit by the 18th — and never skip a nil return. Keep your records in one place and the whole thing takes minutes. For the invoice side of compliance, read FBR sales tax invoice requirements.