Missing a GST/HST filing deadline triggers real, calculable costs — and the size of that cost depends heavily on one thing most people don't realize matters: whether money is actually owed on the return.

Does a Late GST/HST Return Always Come With a Penalty?

No — the late-filing penalty only applies if there's a balance owing when the return is filed. A business whose return shows a refund or no amount owing generally isn't subject to the late-filing penalty, though the refund itself is still delayed until the return is actually filed.

How the CRA Calculates the Late-Filing Penalty

When a balance is owing, the penalty is 1% of the amount owing, plus 25% of that 1% penalty for each full month the return remains outstanding, up to a maximum of 12 months. Once 12 full months have passed, the late-filing penalty has reached its maximum of 4% of the balance owing.

For example: a business that owes $8,000 and files three months late would owe an $80 base penalty, plus $20 for each of the three full months overdue. Total late-filing penalty: $140.

Interest Accrues Separately From the Penalty

On top of any late-filing penalty, interest compounds daily on the unpaid balance, starting the day after the amount was due, at the CRA's prescribed interest rate. That rate is reviewed and reset every calendar quarter, so a business estimating what a late payment will actually cost should check the current rate directly rather than relying on a figure from a previous quarter.

What Happens If a Business Doesn't File at All

Beyond penalties and interest, a business that doesn't file can eventually have the CRA assess the amount owing based on the information available to it — an estimate that's often less favourable than what an accurate return would show.

Filing Late Still Beats Not Filing

Even when full payment isn't possible by the deadline, filing on time is usually far better than waiting to file. Interest may still apply to any unpaid balance, but filing on time avoids the late-filing penalty entirely — since the penalty is tied to the filing date, not the payment date. Filing and payment are two separate obligations, and treating them that way is what actually limits the cost of a cash-flow crunch.

Often, a late return isn't really about cash flow — it's about not trusting the numbers enough to file yet. If that's what's actually holding things up, that's exactly the kind of situation the RSB Guide and Margot can help work through.

Whether a business needs to register and file GST/HST in the first place is the question that comes before any of this — RSB's GST/HST quiz is the place to start if that's still unclear.

FAQ

Should I file my GST/HST return if I can't pay it? Yes. Filing and payment are separate obligations. Filing on time avoids the late-filing penalty even when the balance can't be paid immediately, though interest will generally continue to accrue on whatever remains outstanding.

Can a late-filing penalty be waived or reduced? In some cases, yes — the CRA's Taxpayer Relief Program can reduce or cancel penalties and interest in situations like illness, natural disaster, or CRA-caused delays, though it's not guaranteed and requires a formal request.

Does filing electronically instead of on paper avoid any penalties? Filing method doesn't affect the late-filing penalty itself, but electronic filing is required for most GST/HST registrants, and filing on paper when electronic filing is required can trigger a separate penalty.

If a return shows a small refund, is there still a risk in filing late? The late-filing penalty itself generally doesn't apply in a refund position, but filing late still means waiting longer to actually receive that refund.

Does a missed instalment payment carry the same penalty as a missed filing deadline? No — missed or insufficient instalment payments are treated separately, generally resulting in instalment interest rather than the late-filing penalty, though both can apply in the same year if both issues occur.

Follow the system. File with confidence.