When you're registered for GST/HST, every dollar of tax you pay on business purchases is a dollar you can get back — if you know how to claim it properly. Input tax credits (ITCs) are the mechanism that prevents GST/HST from becoming a permanent cost of doing business. Understanding how they work, what qualifies, and what the rules say about documentation can make a meaningful difference to your cash flow and year-end numbers.
Input tax credits (ITCs) allow GST/HST registrants to recover the GST/HST they paid on purchases and expenses used in their commercial activities. The core logic of the GST/HST system is that the tax should ultimately fall only on final consumers — not on businesses along the supply chain. ITCs are how that principle works in practice.
When you file your GST/HST return, you don't simply remit everything you collected. Instead, your net remittance equals the GST/HST you collected on sales minus the ITCs you're entitled to claim on business expenses. If you collected $4,000 in GST and paid $1,500 in GST on legitimate business purchases, you remit only $2,500. In some periods — particularly for businesses with large capital purchases — ITCs can exceed GST collected, resulting in a refund from the CRA.
Any business or self-employed individual registered for GST/HST can claim ITCs on expenses incurred in the course of commercial activities. Commercial activities include most taxable and zero-rated supplies — essentially, anything where you charge GST/HST or would if the supply weren't zero-rated.
If your business is fully commercial, you can generally claim ITCs on 100% of eligible expenses. If your operations are a mix of commercial and exempt activities (such as certain financial services, residential rentals, or healthcare), you can only claim ITCs to the extent the purchases relate to the commercial side. This requires a reasonable allocation method, which the CRA may ask you to justify.
The general rule is that any purchase on which you paid GST/HST and that relates to your commercial activities is eligible. Common qualifying expenses include:
When an expense serves both business and personal purposes, you can only claim an ITC for the business portion. Vehicles are the most common example. If you use a vehicle 60% for business and 40% for personal trips, you can claim 60% of the GST/HST paid on operating costs — fuel, repairs, insurance where applicable — as an ITC. The same logic applies to a home office, a cell phone used partly for personal calls, or any other mixed-use asset.
You need to track the business-use percentage in a defensible way. For vehicles, a mileage log is the standard and the CRA's expected method. For home offices, the percentage of home square footage dedicated to business use is the typical calculation. Guessing or rounding generously is a risk — the CRA can and does audit ITC claims, particularly on vehicles and home expenses.
This is where many businesses lose ITCs they're legitimately entitled to. The CRA sets tiered documentation requirements based on purchase amount, and failing to retain the right records means forfeiting the credit if you're audited.
For purchases of less than $30 (including GST/HST), a simplified receipt is sufficient. This just needs to show the supplier name, the date, and the total amount paid. Most small receipts — coffee for a client meeting, a pack of pens — satisfy this standard automatically.
For purchases in this range, your supporting document must show: the supplier's name (or trading name), the date of the transaction, the total amount paid, and a separate disclosure of either the GST/HST amount or a statement that GST/HST is included along with the applicable rate. Most business receipts and invoices in this range will include these details automatically.
For larger purchases, the CRA requires a full tax invoice. This must include: the supplier's name and business number (their 9-digit BN followed by RT and the account number), the date of the supply, a description of the goods or services, the total amount of the supply, the GST/HST amount charged or a statement that GST/HST is included and the rate, and — in some cases — your name or trading name as the purchaser.
The business number requirement is significant. If a supplier charges you GST/HST but doesn't provide their BN on the invoice, you should ask for it. Paying GST on an invoice that lacks the BN leaves your ITC claim vulnerable. This is also a red flag for CRA auditors — if a supplier collected GST without being registered, the ITC may be disallowed entirely.
ITCs are reported on line 108 of your GST/HST return (or the equivalent line on a simplified or quick-method return). The net amount remitted — or refunded — flows from line 109. If you file electronically through My Business Account, the process is the same; the labels correspond to the same data fields.
The frequency at which you file your GST/HST return determines how often you can claim ITCs. Annual filers can only recover ITCs once per year, which can create cash flow pressure for businesses with significant input costs. Monthly or quarterly filing accelerates ITC recovery and is worth considering if your business regularly pays substantial GST/HST on inputs.
You have four years from the due date of the return in which you could have first claimed the ITC to actually claim it. For most registrants, this means four years from the due date of the return for the period in which the expense was incurred. If you missed claiming an ITC in a prior period, you can still include it in a later return — but don't let it sit indefinitely. Once the four-year window closes, the credit is gone permanently.
The Swift Accounting Calgary team regularly helps clients recover unclaimed ITCs from prior years during GST/HST return preparation and CRA audit support. A missed ITC from a capital purchase two years ago can still be claimed.
Not every business expense with GST/HST attached generates an ITC. The CRA blocks or restricts certain categories:
If your business uses the Quick Method of accounting for GST/HST, the rules are fundamentally different. Under the Quick Method, you remit a flat percentage of your GST/HST-inclusive revenue rather than tracking actual GST collected and ITCs in detail. The trade-off is simplicity — but you forfeit the ability to claim ITCs on most purchases. The one exception is capital real property, on which ITCs remain available even for Quick Method users.
For businesses with high input costs relative to revenue — such as those buying a lot of taxable goods for resale — the Quick Method may actually cost more than the regular method. It's worth running the numbers before electing or staying on the Quick Method.
Good habits at the point of purchase save significant time and money later:
If your bookkeeping has gaps or you're unsure whether specific expenses qualify, the team at Swift Accounting in Calgary can review your records and ensure your GST/HST returns reflect everything you're entitled to claim.
The CRA requires supporting documentation, and the absence of a receipt puts the ITC at risk in an audit. For small purchases under $30, a credit card statement may be acceptable in combination with other evidence. For larger purchases, the CRA generally expects an invoice or receipt meeting the appropriate tier requirements. Reconstructing missing records is possible in some cases, but it's far better to retain originals from the outset.
You cannot claim an ITC for GST paid to an unregistered supplier. The ITC system is predicated on the supplier remitting the GST they collected to the CRA. If they weren't registered and didn't remit it, your claim has no basis. You may be able to pursue a civil remedy against the supplier, but the CRA will disallow the ITC regardless.
You can claim ITCs on inventory and capital property you held at the time of registration, provided you still hold them and they are for use in commercial activities. There are specific rules and calculations for these "deemed" ITCs, and the timing matters. Purchases of services made before registration generally do not qualify. If you've recently registered, a review of pre-registration assets is worthwhile.
Generally, four years from the due date of the return for the reporting period in which the ITC first became claimable. For most annual filers, this means you can look back approximately four years. However, for large businesses (those with annual taxable supplies exceeding $6 million), the window is compressed to two years. If you believe you have missed ITCs, act promptly — the deadline is firm and the CRA will not grant extensions.
Getting ITCs right is one of the most reliable ways to reduce the actual cost of running your business. If you'd like help reviewing your GST/HST filing position or catching up on missed claims, contact Swift Accounting to speak with a Calgary-based accountant.
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