Credit card interest in Canada is calculated daily, compounds continuously, and can turn a manageable balance into a years-long debt spiral. Here’s exactly how it works — and how to avoid paying it entirely.
The Grace Period: How to Pay Zero Interest
Every Canadian credit card offers a grace period — an interest-free window between your statement close date and your payment due date, typically 21 days (FCAC-mandated minimum).
How the grace period works:
- Your billing cycle closes (e.g., May 31)
- Your statement is issued showing everything you owe
- Your payment due date arrives (e.g., June 21)
- If you pay the full statement balance by June 21 → $0 interest charged
The catch: The grace period only applies if you paid your previous statement in full. If you carried any balance from the prior month, new purchases begin accruing interest immediately — no grace period until you return to a zero balance.
How Interest Is Calculated: The Daily Method
Canadian credit cards calculate interest using a daily periodic rate:
Daily rate = Annual rate ÷ 365
At 19.99% APR:
- Daily rate = 19.99% ÷ 365 = 0.05477% per day
Interest is applied to your average daily balance — the average of your balance on each day in the billing period.
Example:
- Day 1–15: $0 balance (just paid in full)
- Day 16: $1,000 purchase
- Day 16–30: $1,000 balance (15 days)
- Average daily balance = (0 × 15 + 1,000 × 15) ÷ 30 = $500
- Interest = $500 × 0.05477% × 30 = $8.22
Interest by Card Type
| Type | Rate | Grace Period | Interest Starts |
|---|---|---|---|
| Purchase | 19.99% | Yes (if balance was $0) | After due date if unpaid |
| Cash advance | 22.99% | No | Immediately |
| Balance transfer | Promo rate (0%–3.99%) or 19.99% | Depends on promo terms | Per promotional agreement |
Cash advances are particularly dangerous — the 22.99% rate applies from the moment you take the advance, with no grace period. Avoid using credit cards for cash.
Compounding: How Small Balances Grow
Interest compounds daily — yesterday’s interest is added to your balance, and interest is charged on that new total tomorrow.
On a $3,000 balance at 19.99%, paying minimum only (~$75/month):
- Month 1: $50 in interest; ~$25 reduces principal → $2,975 balance
- Month 12: Still owe ~$2,700 (only reduced by $300 in a year)
- Year 5: Still owe ~$1,900
- Year 14: Finally paid off — total interest paid: ~$4,100
That $3,000 balance cost $7,100 total.
How to Avoid Interest Entirely
- Pay the full statement balance every month — not just the minimum, not the current balance — the statement balance
- Set up autopay for the full statement balance if your bank supports it
- Never take cash advances on a credit card
- Don’t miss payments — missing triggers penalty rates on some cards
What Happens When You Miss a Payment?
- Late fee: $25–$45 immediately
- Interest accrues: From the statement date (no grace period is restored until you repay the full balance)
- Credit score impact: Reported to Equifax and TransUnion after 30 days
- Penalty APR: Some issuers (check your cardholder agreement) can raise your rate after missed payments
Related Articles
- How to Read Your Credit Card Statement
- Minimum Payments Explained
- Credit Card Grace Period in Canada
- What Is APR on a Credit Card?
- Best Low-Interest Credit Cards in Canada
Interest rate figures reflect standard industry rates as of 2026. Your cardholder agreement governs your specific rates. See our Advertiser Disclosure.