For something that causes so much anxiety, the GST/HST return is conceptually simple. You're a collection agent for the government: you charge tax on your sales, you pay tax on your purchases, and the return reconciles the two. If you collected more than you paid, you send the difference to the CRA. If you paid more than you collected, you get a refund.
Everything else — the line numbers, the filing method, the deadlines — is mechanics around that one idea. Let's walk through it the way I would with a client filing for the first time.
- Net tax = GST/HST you collected − GST/HST you paid on business purchases (your input tax credits, or ITCs). That's the whole return in one line.
- Line 101 = your sales. Line 105 = tax collected. Line 108 = ITCs. Line 109 = net tax (105 − 108).
- File online via GST/HST NETFILE or CRA My Business Account — for most filers it's mandatory, and line 109 calculates itself.
- Set the tax aside as you collect it. The GST/HST you charge isn't your money — it's the CRA's, held in trust. Spend it and filing day becomes a crisis.
- Keep your receipts. No valid receipt, no ITC — you can only claim tax you can prove you paid.
Read on for the step-by-step, the filing methods, a worked example, the common mistakes, and a real-world story.
You're a collection agent, not a taxpayer
The single most important thing to understand: the GST/HST you charge your customers was never your money. You collect it on the government's behalf and hold it in trust until you remit it. Your own tax cost — the GST/HST you paid on business expenses — gets credited back to you through input tax credits (ITCs). The return nets the two.
Step 0 — know your reporting period and deadline
Your return covers a reporting period — monthly, quarterly, or annual — set by your revenue and your own election. The filing and payment deadline depends on that frequency (monthly/quarterly: one month after the period; annual: three months after year-end, or the June 15 / April 30 split for sole proprietors). Get your exact dates from the 2026 deadline calendar before you begin.
The four numbers that make up the return
A standard return comes down to four figures. Here's what each means in plain language:
| Line | What it is |
|---|---|
| Line 101 | Your total sales and revenue for the period (before tax). Informational — it doesn't change the math. |
| Line 105 | Total GST/HST you collected or that became collectible on your sales. |
| Line 108 | Total input tax credits — the GST/HST you paid on business purchases and expenses. |
| Line 109 | Net tax = line 105 − line 108. Positive, you owe; negative, you're refunded. |
Source: CRA, "Instructions for preparing a GST/HST return" and "Calculate the net GST/HST" — line 101 reports sales; line 105 is total GST/HST collected (plus adjustments at 104); line 108 is total ITCs (plus adjustments at 107); line 109 net tax is line 105 minus line 108, and is calculated automatically when you file electronically.
(You may also see lines 110/405/111 for instalments, certain adjustments, and rebates — most small filers leave these blank. If you use the Quick Method, you don't claim most ITCs and the math works differently — see that article.)
Filing, start to finish
- Total your sales (line 101). Pull your revenue for the reporting period from your books — pre-tax. Clean monthly bookkeeping makes this a thirty-second lookup instead of an afternoon.
- Total the GST/HST you collected (line 105). The tax you charged on those sales. Your accounting software's sales-tax report gives you this directly.
- Total your input tax credits (line 108). Add up the GST/HST you paid on legitimate business purchases — supplies, software, professional fees, equipment. You need valid receipts showing the supplier's GST/HST number; no number, no ITC.
- Let line 109 calculate. Net tax is 105 minus 108. File electronically and it's done for you.
- File and pay (or receive your refund). Submit through NETFILE or My Business Account, then pay any balance by the deadline — interest runs from the payment date if you're late.
- Keep your records. Hold your receipts and working papers for six years in case the CRA reviews the return.
You collected $7,800, you're credited $2,100 for tax you paid, you remit the $5,700 difference. If your ITCs had exceeded the tax collected (say, a quarter with a big equipment purchase), line 109 would be negative and the CRA would refund you.
Filing methods
Most businesses are required to file electronically. Your options:
- GST/HST NETFILE — the CRA's free online filing service; enter your figures and submit.
- CRA My Business Account — file from your secure CRA portal, where you can also pay and see your balance.
- Through your accounting software — QuickBooks and Xero both produce a return-ready summary and, in many cases, let you file directly.
- Your bookkeeper or accountant files on your behalf — the path most owners eventually choose, because it folds into the monthly books.
Source: CRA, "Complete and file a GST/HST return" — electronic filing (GST/HST NETFILE, My Business Account, or through a third party) is required for most registrants; line 109 is calculated automatically on electronic returns.
What goes wrong — and how to avoid it
- Spending the tax you collected. The biggest one. That HST sitting in your account isn't profit — it's the CRA's money in trust. Move it to a separate savings account as you collect it.
- Missing ITCs. Every business purchase with GST/HST on it is a credit you're entitled to. Lose the receipts and you overpay — owners leave real money on the table here.
- Claiming ITCs you can't support. The opposite error: claiming credits with no valid receipt, or on personal expenses. That's what gets reversed in a review. (The documentary rules.)
- Filing a "nil" return wrong — or not at all. Even with no sales, if you're registered you generally still have to file.
- Confusing filing and payment dates. Interest runs from the payment date even if your return isn't late.
Ben spent the tax he was holding
Meet Ben, who runs Tallgrass Print Co., a screen-printing shop in Brandon, Manitoba. His first year registered, business was good — he charged GST on every order and watched his bank balance climb. What he didn't separate in his mind was that a chunk of that balance was GST he'd collected, not earned. He spent against it: new equipment, a deposit on a larger space.
When his first annual return came due, the math was brutal. He'd collected about $9,400 in GST over the year. He'd kept almost no receipts for his own purchases, so he could only support $1,200 in ITCs. Net tax owing: roughly $8,200 — and the money was long gone into equipment and rent.
He hadn't made a filing error. He'd made a cash error months earlier — treating trust money as income, and throwing away the receipts that would have lowered the bill.
Ben scraped the payment together late and ate some interest. The double sting: with better records, his ITCs would likely have been several thousand dollars higher, cutting the bill substantially.
What should have happened
Two habits would have prevented all of it. First, set the GST aside — every time he collected tax, move it to a separate account so it's there at filing. Second, capture every receipt — each one with GST on it is an ITC that directly reduces what he owes. Done monthly instead of in a year-end panic, the return is a non-event.
Get two numbers right, and the rest is easy
The GST/HST return intimidates people because of the form, but the substance is one subtraction: tax collected minus tax paid. Keep the tax you collect in a separate account so it's there when it's due, capture every receipt so you claim every credit you're owed, and file electronically so the math does itself. Do it monthly alongside clean books and the return stops being a deadline you dread and becomes a five-minute confirmation.
Want your GST/HST handled, every period?
With clean monthly books, your return is calculated, filed, and paid on time without you touching a form. A 20-minute call is enough to see what that would look like for your business.
Book a Free 20-Minute CallThis article is for informational purposes only and does not constitute tax, legal, or accounting advice. GST/HST rules, rates, and line numbers can change, and your obligations depend on your situation, province, and reporting method. The figures used are illustrative. Consult a qualified professional or the CRA about your own return.
Primary sources, linked so you can read and interpret them yourself. Government links open on official Government of Canada websites.
- CRA — Complete and file a GST/HST return (filing methods and overview)
- CRA — Instructions for preparing a GST/HST return (line-by-line)
- CRA — Calculate the net GST/HST (line 109)
- CRA — Reporting requirements and deadlines (GST/HST)
- Related reading: When to Register for GST/HST, No Valid Invoice, No ITC, The Quick Method, and The 2026 Tax Deadline Calendar
Rodney Maiato is the founder of CDL Accounting Solutions, a remote bookkeeping practice helping Canadian incorporated small businesses keep clean, audit-ready books without the year-end scramble. He brings 15+ years in accounting — from junior accountant to assistant controller, where he managed a team of 7 and oversaw the books of 25+ companies, plus payroll for 100+ employees across several provinces — and is a Payroll Compliance Professional (PCP) Candidate with the National Payroll Institute. He also builds the automation behind CDL, including its text-in receipt intake system.