Find out whether you need to register for GST/HST, estimate what you owe or get back after input tax credits, and see the late-filing penalty and interest if a return is late. Built for Ontario businesses charging 13% HST.
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Rates used: HST rate, Ontario: 13% (source); Small supplier threshold (taxable supplies, 4 consecutive quarters or 1 quarter): $30,000 (source); GST/HST late-filing penalty: base: 1% (source); GST/HST late-filing penalty: per full month: 0.25% (source); GST/HST late-filing penalty: maximum months: 12 (source); CRA prescribed rate on overdue taxes, CPP/EI and GST/HST: 7% (Oct–Dec 2026) (source).
Last updated: October 18, 2026
How the calculator works
Small-supplier test: enter your taxable sales for the last four calendar quarters and your biggest single quarter.
Net tax for a period: enter your taxable sales and the business purchases you paid HST on. The calculator subtracts your input tax credits (ITCs) from the HST you charged.
Late return: tell it whether the return was filed and paid, and when. It adds the late-filing penalty and daily-compounded interest.
When you have to register
You are a small supplier, and don’t have to register, while your worldwide taxable sales (including those of associated businesses) stay at or under $30,000 in a single calendar quarter and over the last four consecutive calendar quarters.
Over $30,000 in one quarter: you must register, and you charge GST/HST from the sale that took you over.
Over $30,000 across four quarters: you stop being a small supplier at the end of the month after that quarter.
Taxi and ride-share drivers: must register from their first fare, whatever their sales.
Voluntary registration: lets you claim ITCs on your business purchases before you reach the threshold.
If a return with a balance owing is filed late, the penalty is 1% of the amount owing plus 0.25% of it for each full month late, up to 12 months. There is no late-filing penalty when nothing is owing, but you still have to file. Interest on the balance compounds daily at the prescribed rate for overdue amounts, 7% for October 1 to December 31, 2026.
Monthly and quarterly returns are due one month after the end of the period. Annual returns are due three months after the fiscal year-end, except sole proprietors with a December 31 year-end, who file by June 15 and pay by April 30.
Want us to handle your GST/HST?
T-Ledgers is a CPA-led accounting firm practising since 2020, led by Wajahat Ajmal, CPA, FCCA. We have worked with 202 clients, with a combined $60 million in client revenue.
When your taxable sales go over $30,000 in a single calendar quarter or over four consecutive calendar quarters. Over $30,000 in one quarter, you register right away; over four quarters, you stop being a small supplier at the end of the month after that quarter.
1% of the amount owing plus 0.25% of it for each full month late, up to 12 months, plus daily-compounded interest at the prescribed rate. There is no late-filing penalty when nothing is owing.
One month after the end of a monthly or quarterly period. Annual filers: three months after year-end; sole proprietors with a December 31 year-end file by June 15 and pay by April 30.
Talk to a CPA about your GST/HST
Book a free 30-minute call. We’ll check whether you need to register and what your returns should show.
Call (866) 254-5368 or email info@tledgers.ca. A 24/7 receptionist answers, so a real person picks up.
