HST in Ontario: when to register, and what happens if you file late.

By Maaz · Evolve Financial · June 24, 2026 · 6 min read

If you run a small business in Ontario, here's the short version: you must register for GST/HST once your taxable sales pass $30,000 — either in a single calendar quarter or over four consecutive quarters. HST in Ontario is 13%, you charge it on most sales, and you file a return on a schedule the CRA assigns you. Miss a filing when you owe money, and the penalties (plus daily interest) start adding up.

Below is everything an Ontario owner actually needs to know about HST — when to register, how much to charge, when to file, and exactly what late filing costs you.

When do you have to register for HST in Ontario?

You're considered a "small supplier" — and you don't have to register — as long as your taxable revenue stays under $30,000 over four consecutive calendar quarters. The moment you cross that line, the rules change:

• If you exceed $30,000 in a single quarter: you stop being a small supplier that day. You must register and start charging HST immediately — including on the sale that pushed you over the line.
• If you cross $30,000 gradually across four quarters: you stop being a small supplier at the end of the month following that quarter, and you generally have to register within 29 days of your first sale after that.

Even under $30,000, plenty of Ontario businesses register for HST voluntarily. Why? Because once you're registered you can claim input tax credits (ITCs) — the HST you paid on business expenses comes back to you. If you're buying inventory, equipment or services, that can put real money back in your pocket.

How much is HST in Ontario, and what you charge

HST in Ontario is 13% (5% federal GST + 8% provincial). Once registered, you charge 13% on most goods and services, collect it from customers, and remit it to the CRA. The key thing owners forget: that collected HST isn't your money — it's the government's, sitting in your account until you file. Set it aside so it's there when the return is due.

HST filing deadlines: how often do you file?

The CRA assigns your filing frequency based on your revenue — annually, quarterly or monthly. Most small Ontario businesses file annually or quarterly. Whichever you're assigned, the rule is the same: file on time, every time, even if you have nothing to remit. A clean set of books makes this a 20-minute job instead of a weekend of panic.

What happens if you file or pay HST late?

The CRA charges a late-filing penalty only when you owe money on the return. The formula is A + (B × C), where A is 1% of the amount owing, B is 25% of A, and C is the number of months your return is late (up to 12). In plain terms: 1% of what you owe, plus 0.25% for each full month late, to a maximum of 12 months.

On top of the penalty, the CRA charges interest on overdue amounts — currently around 7% per year, compounded daily — from the day payment was due. A quick example: owe $1,000 and file three months late, and the penalty is $17.50 ($10 + $2.50 × 3), plus interest. Small on $1,000; much less fun on $15,000.

How to stay on top of HST without the stress

The owners who never worry about HST all do the same three things: they keep their books reconciled monthly, they set aside the HST they collect, and they know their filing date before it arrives. That's exactly what we handle for clients — clean books year-round and filings done on time, so HST is a non-issue. If you want a hand, see our tax filing service or our monthly bookkeeping.

Frequently asked questions

Do I need to register for HST if I'm under $30,000 in Ontario?

No — under $30,000 in taxable sales over four consecutive quarters, you're a small supplier and registration is optional. That said, many Ontario owners register voluntarily so they can claim back the HST they pay on expenses (input tax credits). If you're spending on inventory or equipment, it often pays for itself.

How much is HST in Ontario and how often do I file?

HST in Ontario is 13%. Once registered, you charge it on most sales and file a return on the schedule the CRA assigns — usually annually or quarterly for small businesses, monthly for larger ones. You file even in periods where you owe nothing, so staying organised matters more than the frequency itself.

What are the CRA penalties for filing HST late?

If you owe on the return, the penalty is 1% of the balance plus 0.25% for each full month you're late, up to 12 months. The CRA also charges interest on overdue amounts — currently about 7% per year, compounded daily — from the due date. File on time and you avoid the penalty entirely, even if you can't pay in full yet.