Input Tax vs Output Tax: How Sales Tax Adjustment Works

At the centre of how sales tax works in Pakistan is one simple idea: you pay FBR the difference between the tax you charge on sales and the tax you pay on purchases. Those two amounts are your output tax and input tax, and the process of setting one against the other is called adjustment.

Once this clicks, the whole sales tax system makes far more sense. This guide explains both terms, how the offset works each month, and what happens when your input tax is larger than your output tax.

Output tax: what you charge

Output tax is the sales tax you charge your customers on your taxable sales. When you issue an invoice for taxable goods at the standard rate, the tax added on top is your output tax. You are collecting it on the government's behalf — it is not your income.

Input tax: what you pay

Input tax is the sales tax you pay your suppliers when you buy goods and services for your business. Because you are a registered person, this tax is generally not a final cost to you — you can offset it against your output tax, provided the purchase is eligible and properly documented.

How the adjustment works

Each tax period, the calculation is essentially:

Output tax − Input tax = Amount payable to FBR

In practice this means:

1. Total up the output tax you charged on all taxable sales in the period;
2. Total up the eligible input tax you paid on purchases in the period;
3. Subtract input from output;
4. If output is greater, you pay the difference to FBR;
5. If input is greater, you have a credit to carry forward (or, in some cases such as exports, potentially claim as a refund).

A simple worked example

Imagine that in a month:

• You charged Rs 180,000 of output tax on your sales;
• You paid Rs 120,000 of eligible input tax on your purchases.

Your net sales tax payable would be Rs 180,000 − Rs 120,000 = Rs 60,000. You collected Rs 180,000 from customers but, because you already paid Rs 120,000 to suppliers, you only hand FBR the Rs 60,000 difference. (These figures are illustrative only, to show the mechanism.)

When input tax exceeds output tax

Sometimes your input tax for a period is larger than your output tax — for example when you have made a big purchase, or when much of your output is zero-rated. In that case you do not usually get an immediate cash payment. Instead the excess is generally carried forward to offset against future output tax.

Exporters, whose sales are zero-rated, often sit in this position and may be able to claim a refund under the applicable rules. Because refund procedures change, confirm the current process with FBR or your tax adviser.

Why documentation is everything

You can only claim input tax you can prove. That means keeping valid purchase invoices that show the tax, from suppliers who are properly registered. The rise of FBR Digital Invoicing — with each invoice carrying an IRN and QR — makes this trail cleaner, because genuine, reported invoices are easy to verify.

Common reasons input tax is disallowed

• The purchase invoice is missing, incomplete or from an unverifiable supplier;
• The purchase is not eligible for input tax adjustment under the rules;
• The input relates to exempt supplies, where recovery is generally not allowed;
• The claim falls outside the permitted time limits.

Since the detailed rules on eligibility and timing change, check specifics with a tax adviser rather than assuming every purchase qualifies.

Where the adjustment happens: your return

The input-versus-output calculation is done through your monthly sales tax return and its annexures, which list your sales and purchases. The return is where the two sides meet and your net position is established. See how to file your monthly sales tax return for the full process.

Frequently asked questions

Is input tax my money back?

Not exactly. Input tax is offset against the output tax you owe, reducing your payment to FBR. It is a credit within the system rather than a cash refund, except in specific situations like exports.

What if I forget to claim some input tax?

There are usually time limits for claiming input tax. If you miss a claim, speak to your adviser about whether it can still be adjusted within the permitted period.

Can I claim input tax on everything I buy?

No. Only eligible purchases with valid documentation qualify, and input relating to exempt supplies is generally not recoverable. See our FAQs for more detail.

Iris Accounts records your input and output tax as you buy and sell, and works out your net position for the period automatically, so your monthly adjustment is accurate without manual tallying.