HST/GST Registration in Ontario: When You Must Register and When to Do It Early

Every Canadian business providing taxable supplies must register for GST/HST once revenues exceed $30,000 in a single calendar quarter or over four consecutive calendar quarters. In Ontario, HST is 13% (5% federal + 8% provincial). Here's a practical guide to navigating registration.

The $30,000 Threshold: How It Works

You need to track your taxable revenues rolling — both in the current calendar quarter and cumulatively over the past four quarters. The moment you exceed $30,000 in either window, you must register. You then have 29 days from the day you exceeded the threshold to file for registration. After that deadline, penalties apply.

Why Voluntary Registration Often Makes Sense

Registering before you hit the threshold lets you claim Input Tax Credits (ITCs) — refunds of the HST you paid on business expenses — from the date of registration. If you're spending money on equipment, software, rent, or supplies for your business, you're already paying HST. Getting that back via ITCs is real money.

For B2B businesses especially, early registration also removes the question from your clients' minds. A registered supplier looks like an established business. Unregistered suppliers under the threshold can sometimes create friction with larger corporate clients who expect a GST/HST number on invoices.

Zero-Rated vs. Exempt: A Critical Distinction

Not all supplies are taxable at 13%. Some are zero-rated (taxed at 0%) and some are exempt (not subject to HST at all). The difference matters for ITCs:

• Zero-rated supplies (basic groceries, prescription drugs, most exports, agricultural products): You charge 0% HST, but you CAN claim ITCs on your business expenses related to those supplies.
• Exempt supplies (residential rent, health care services, educational services, most financial services): You do NOT charge HST, and you CANNOT claim ITCs on related expenses.
• Most Ontario businesses providing services to consumers or other businesses are making taxable supplies at 13%.

Filing Frequency

The CRA assigns a filing frequency based on your annual taxable supplies: annual (under $1.5M), quarterly ($1.5M–$6M), or monthly (over $6M). Most small businesses start on annual filing. If you have significant ITCs (you pay more HST on inputs than you collect), requesting quarterly filing gets your ITCs back faster — improving your cash flow.

Common Mistakes to Avoid

• Mixing HST collected with operating funds — set aside collected HST in a separate account.
• Missing a quarterly instalment if you owe more than $3,000 — interest and penalties apply.
• Not tracking the split between HST collected and HST paid on expenses — you'll need this for your return.
• Claiming ITCs on personal expenses mixed in with business — the CRA reviews these closely.