HST for Ontario Small Businesses: What You Need to Know Before You Get It Wrong

HST — the Harmonized Sales Tax — is one of the most misunderstood parts of running a small business in Ontario. I've seen it cause everything from minor headaches to five-figure CRA bills. The good news: once you understand how it works, it's completely manageable.

When Do You Have to Register for HST?

In Ontario, you're required to register for HST once your business revenue exceeds $30,000 in a single calendar quarter or over four consecutive quarters. This is called the "small supplier threshold."

You can also register voluntarily before hitting $30,000 — and for many businesses, this is actually the smarter move. Registering early lets you claim Input Tax Credits (ITCs) on your business expenses, which can mean real money back in your pocket.

The Biggest HST Mistake Small Business Owners Make

Spending the HST you collect. This is the number one HST error I see, and it's an expensive one.

When you charge a client $1,000 + HST, you collect $1,130. That extra $130 is not your money — it belongs to the CRA. You're holding it in trust until your next HST remittance. Spending it and then not having it when your remittance is due is how businesses end up with CRA debt.

The fix: Open a separate savings account and transfer your HST collected into it every time you receive a payment. Treat it like it doesn't exist.

Understanding Input Tax Credits (ITCs)

The good news about HST: you can claim back the HST you pay on business expenses. These are called Input Tax Credits. If you pay $500 + HST for a business expense, you can claim back the $65 in HST you paid — reducing your net remittance to the CRA.

To claim ITCs, you need proper receipts showing the HST paid and the supplier's HST registration number. This is one of the reasons clean bookkeeping pays for itself — missed ITCs are money left on the table.

HST Filing Periods: Which One Is Right for You?

• Annual filing: Available if your revenue is under $1.5M. Simplest option but requires a large lump-sum payment once a year.
• Quarterly filing: Most common for small businesses. Manageable payment amounts, lower risk of a surprise bill.
• Monthly filing: Required if your revenue exceeds $6M. Also useful if you consistently receive more HST than you remit (e.g., you export goods).

Quick Reference: HST Rate in Ontario

Ontario's HST rate is 13% (5% federal GST + 8% provincial). Most goods and services are taxable at 13%. Some items are zero-rated (basic groceries, prescription drugs) or exempt (residential rent, most financial services).

Get It Right From the Start

HST compliance is one of those things that's much easier to set up correctly from the beginning than to fix after the fact. Our bookkeeping packages include HST tracking and remittance preparation so you never have to worry about it. Book a free consultation to get your HST sorted out properly.