The Complete GST/HST Guide for Ontario Small Businesses

When Do You Need to Register?

You must register for a GST/HST account when your total taxable revenues exceed $30,000 in a single calendar quarter or over four consecutive calendar quarters. This threshold applies to most businesses, though certain types (taxi operators, non-residents, etc.) must register immediately regardless of revenue.

You can also register voluntarily before reaching the threshold — which is often beneficial because it allows you to claim input tax credits (ITCs) on your business purchases from day one.

Ontario's HST Rate

Ontario charges the Harmonized Sales Tax (HST) at a rate of 13% — combining the 5% federal GST and Ontario's 8% provincial component. This applies to most goods and services sold in Ontario.

Some supplies are zero-rated (taxed at 0%, such as basic groceries and prescription drugs) or exempt (no HST charged and no ITCs claimable, such as most financial services and residential rent). Understanding which category your products or services fall into is essential.

Input Tax Credits: Recovering the HST You Pay

One of the most important concepts in GST/HST is the input tax credit (ITC). When you pay HST on business purchases, you can claim that amount back against the HST you collect from customers. You only remit the difference.

To claim ITCs, you need valid supporting documentation: supplier name, date, total amount, HST amount (or a statement that HST is included), and the supplier's GST/HST registration number for purchases over $30. Keep all receipts — the CRA will ask for them.

Filing Periods and Deadlines

Your filing frequency depends on your annual taxable revenues: monthly (over $6 million), quarterly ($1.5 million to $6 million), or annually (under $1.5 million). Most small businesses file annually or quarterly.

Annual filers have until three months after their fiscal year-end to file and pay. Quarterly filers must file within one month of the quarter-end. Missing deadlines triggers penalties of 1% of the balance owing plus 25% of that 1% for each full month the return is late, up to 12 months.

The Quick Method: A Simpler Option for Small Businesses

If your annual taxable revenues are under $400,000, you may be eligible for the Quick Method of accounting for GST/HST. Instead of tracking every ITC, you remit a fixed percentage of your gross revenues (including HST collected).

For service businesses in Ontario, the Quick Method rate is 8.8% of revenues (including HST). This is often lower than the actual HST owing under the regular method, making it a genuine tax saving for many service businesses. Consult your accountant to determine if it's right for you.

Common GST/HST Mistakes to Avoid

Here are the mistakes we see most often:

• Not registering on time — penalties apply retroactively
• Charging HST on exempt supplies (residential rent, medical services)
• Claiming ITCs on personal expenses or meals and entertainment above the 50% limit
• Missing the deadline to file a nil return (required even if you collected nothing)
• Not keeping adequate documentation for ITC claims
• Forgetting to update your filing frequency as your business grows