How do input tax credits work?

What an input tax credit actually recovers

Every GST/HST-registered business pays tax on many of its own purchases: rent, supplies, equipment, professional fees, and inventory. An input tax credit is the mechanism that lets the business claim that tax back, rather than treating it as a cost of doing business the way a final consumer would.

On a GST/HST return, you report the tax you collected from customers and subtract the ITCs you are claiming on your own purchases; the difference is your net tax owing, or a refund if your ITCs exceed what you collected. This is why a business with large upfront equipment or inventory purchases can end up in a refund position even while fully operational and generating sales, and it is also why the mechanic only works for a registrant: an unregistered small supplier pays GST/HST on its purchases with no way to claim it back at all.

Documentation requirements scale with the size of the purchase

The CRA requires more detailed supporting information as the dollar amount of a purchase rises, moving through a few threshold bands rather than one flat rule for every receipt. A small purchase generally needs only basic information like the supplier's name, the date, and the amount of tax paid, while a larger purchase needs the supplier's GST/HST registration number and more transaction detail, and the largest purchases need still more, including the purchaser's name and payment terms.

The exact dollar amounts marking these bands have been adjusted by the CRA over time, so rather than rely on a specific figure here, confirm the current thresholds directly with the CRA or with us before assuming your invoice meets the bar for its purchase size. What matters in practice is keeping the actual invoice or receipt, not just a bank or credit card statement line, since a statement alone rarely carries the supplier detail an ITC claim needs, and a missing GST/HST number on a supplier invoice is one of the more common reasons a claim gets challenged.

The claim window: four years for most registrants

Most GST/HST registrants have four years from the due date of the return for the period in which the ITC first became claimable to actually claim it, so a missed receipt from an earlier period is not necessarily lost. Certain large businesses, generally those with substantial prior-year taxable supplies, face a shorter two-year window instead, which is worth knowing before assuming an old invoice can always be picked up later.

In practice, this window matters most when a bookkeeping catch-up uncovers old, uncoded receipts, or when a business realizes months later that it never claimed the ITC on a large equipment purchase. Filing an adjustment to claim a missed ITC is normal and does not itself trigger extra scrutiny the way an unusually large, unexplained claim might, but the older the receipt, the more important it is to still have the original invoice on hand rather than relying on memory of the purchase.

A business switching bookkeeping systems, or changing accountants, is a common point where older ITCs get missed simply because the new setup starts fresh rather than reviewing what came before. Building a habit of checking the prior year's uncoded or unreviewed expenses before closing the books each year catches most of these before the claim window becomes a concern.

Restrictions and caps on specific categories

Not every business input is fully recoverable, even when it is clearly used for commercial purposes.

• Meals and entertainment are generally restricted to a 50% ITC, mirroring the 50% income-tax deduction limit on the same expenses; see ITCs on meals and entertainment for the exceptions that restore full recovery.
• Passenger vehicles bought or leased by a business are subject to capital cost and lease-cost caps that limit the ITC to a portion of the purchase or lease payments once the vehicle's price passes a set ceiling; confirm the current ceiling before relying on a number, since it is periodically adjusted.
• Club dues, including memberships at a golf, dining, or similar recreational club, generate no ITC at all, even where the membership is genuinely used to entertain clients.
• The personal-use portion of anything purchased for mixed business and personal use is never claimable; only the business-use share of the tax paid qualifies.

These restrictions exist mainly to prevent input tax credits from becoming a backdoor way to fund personal consumption through the business, and they apply regardless of how the purchase was paid for, whether on a corporate card, a personal card later reimbursed, or by direct bank transfer. A bookkeeper coding expenses from a personal card reimbursement should apply the same restrictions and documentation checks as a direct corporate purchase, since the payment method does not change the underlying category of the expense.

How we track ITCs for clients

We code purchases to the right expense categories as they happen, rather than sorting receipts at year-end, so restricted categories like meals and vehicle costs are flagged and capped correctly instead of claimed in full by default. For clients using Dext or similar receipt-capture tools, we set up the coding rules so the documentation requirement for each purchase size is met automatically as receipts come in, and our bookkeeping services include a periodic review specifically to catch ITCs that were missed rather than waiting for a year-end reconciliation to surface them.

Source: CRA — GST/HST for businesses.