Updated Checked by the Tax-Services.ca editorial team How we check
Unclaimed input tax credits can usually still be claimed. If you’re a GST/HST registrant and missed an ITC on an earlier return, the CRA says you can put it on a future return. For most registrants the limit is four years, counted from the period in which you could first have claimed it.
How do you claim input tax credits you missed?
You don’t reopen the old return. You add the forgotten amount to line 106 of a return you’re about to file, along with that period’s regular credits. The CRA page on input tax credits says registrants “can claim those previously unclaimed ITCs on a future GST/HST return.”
So do it soon. Every quarter you wait moves the oldest purchase closer to the cut-off.
The rule itself reads: claim by the due date of the return for the last reporting period that ends within four years after the end of the period in which the ITC could first be claimed. In plain words, take the period of the purchase, add four years, and find the return due for the period that ends by then. For an annual filer who bought something in 2022, that’s the return for the period ending 31 December 2026. That reading comes straight from the CRA wording, so use it as a guide and check your own filing frequency.
How do you find the credits you missed?
Go looking, because they don’t announce themselves. Sam runs a small renovation firm in Halifax and suspects some paint and tool receipts never made it into a return. Here’s how he’d start.
- Pull the purchase records for each period from the last four years.
- Match them against the ITC amounts you actually claimed on each return.
- List every purchase with tax on it that has no credit beside it.
- Check each one is business use and that you have a proper invoice.
- Total the amounts and enter them on the next return you file.
It’s tedious. It also tends to turn up a few hundred bucks that were sitting there the whole time.
Which registrants get a shorter window?
Not everyone has four years. The CRA lists a two-year limit for listed financial institutions. It also applies to businesses over a $6 million threshold, with exceptions for charities and for businesses where 90% or more of supplies are taxable. Most small businesses and sole proprietors sit in the four-year group.
| Type of registrant | Time limit |
|---|---|
| Most registrants and charities | Four years |
| Listed financial institutions | Two years |
| Businesses over the $6 million threshold (with exceptions) | Two years |
How much is a missed credit worth?
Take a $2,500 equipment purchase in Ontario. The GST/HST calculator puts HST at $325, for a total of $2,825. That $325 is the credit, if the purchase is for your business. In Alberta the same $2,500 carries 5% GST, which is $125.
Often all you have is the receipt total. If you paid $1,130 in Ontario, the HST reverse calculator shows a $1,000 price and $130 of HST. Sum up a few of those over three years and the money is real: three receipts like that are $390 of credits.
Keep the limits in mind, though. Some provinces also charge a separate PST or QST. Recovery of that tax wasn’t researched here, so this page covers the federal credit only.
What records do you need for an ITC?
The CRA asks for documentary evidence, and it gets stricter as the purchase gets bigger.
| Purchase | What the record needs |
|---|---|
| Under $100 | Supplier’s name and the invoice date |
| $100 to $499.99 | Adds the GST/HST amount and the supplier’s registration number |
| $500 or more | Adds the buyer’s name, a description of what you bought and the payment terms |
The page also notes reduced documentation for some cases, such as employee reimbursements and taxi fares. Find the paper first. If you can’t, ask the supplier for a duplicate invoice before you file.
Mistakes to avoid when claiming late
The worst is claiming something that isn’t eligible. Personal purchases are out, and so are some club fees. The CRA page lists motor vehicle expenses as possibly eligible, but it doesn’t say how much, so check the details for your case.
Another is claiming an ITC twice, once on the original return and again on the catch-up. Match the amounts to your books.
And check the period and the amount for anything old. A sole proprietor can see how profit feeds into income tax in the self-employed tax calculator, though it leaves out EI, so treat its answer as a rough one.
Where this information comes from
The claim method, the four-year and two-year limits and the record tiers come from the CRA page on input tax credits, read in September 2026. The tax rates in the examples come from our sales tax data for 2026: 13% HST in Ontario and 5% GST in Alberta. Filing through provincial systems, penalties for late filing and how to apply for discretionary relief aren’t covered.
Frequently asked questions
Can I claim an input tax credit I forgot on an earlier return?
Yes. The CRA says registrants can claim previously unclaimed ITCs on a future GST/HST return, within the time limit.
How long do I have to claim an ITC?
For most registrants, by the due date of the return for the last reporting period that ends within four years after the period in which the ITC could first be claimed.
Which registrants have two years?
Listed financial institutions, and businesses over a $6 million threshold, with exceptions for charities and for businesses with 90% or more taxable supplies.
Where do I report the credit?
On line 106 of the GST/HST return, together with the credits for the current period.
What if I lost the invoice?
Ask the supplier for a copy. The CRA sets record requirements that depend on the purchase amount.
- GST, HST, PST and QST explained for every province
Which GST, HST, PST or QST applies where you shop or sell in Canada, the 2026 rates for every province, who must register and how to add or remove tax