Line 20800: How to claim your RRSP deduction without triggering a review

The CRA looks for specific mistakes on line 20800 that can delay your refund or trigger an audit.

Line 20800 on your T1 is where you claim your RRSP deduction - and it's where most people make the mistake that flags their return for review.

The number you put on line 20800 doesn't have to match what you contributed in 2025. You can contribute $5,000 and deduct $3,000. You can contribute nothing and deduct $4,000 from a previous year's contribution. The CRA tracks contributions and deductions separately, and mixing them up is the fastest way to delay your refund.

Here's what actually matters: your deduction room. Check your most recent Notice of Assessment (NOA) - there's a line called "RRSP/PRPP deduction limit for [year]." That's your ceiling. You can deduct up to that amount on line 20800, regardless of when you made the contributions.

The 60-day rule everyone gets wrong

Contributions made between January 1 and March 2, 2026 can be deducted on your 2025 tax return. Most people know this. What they don't know is that the CRA expects you to specify which year you're deducting them for when you contribute.

If you contributed $6,000 on February 15, 2026 and want to deduct it on your 2025 return, that's fine. But if you already maximized your 2025 deduction room, you can't. The TaxSplit.ca calculator shows your exact deduction room based on last year's earned income.

What triggers a review

The CRA's computer flags returns where line 20800 exceeds your deduction limit. It also flags returns where you claim a deduction but have no record of contributions. If you contributed through payroll deductions, those appear on your T4 in box 20. If you made direct contributions, you should have received an RRSP contribution receipt.

Missing receipts don't disqualify the deduction, but they slow things down. The CRA will ask for proof, and while they're asking, your refund waits.

The carry-forward strategy

You don't have to use your RRSP deduction room immediately. If you're expecting a promotion or bonus next year, you might contribute now but save the deduction for when you're in a higher tax bracket. At $90,000 in Ontario, an RRSP deduction saves you about 43 cents per dollar. At $60,000, it's about 31 cents per dollar.

To carry forward the deduction, contribute but don't claim anything on line 20800. The contribution shows up on next year's NOA as unused deduction room.

The spousal RRSP catch

If you contributed to a spousal RRSP, you claim the deduction on your return - not your spouse's. This trips up couples who split their tax preparation. The contribution reduces your deduction room, not theirs, and goes on your line 20800.

Your 2025 contribution limit is $32,490 or 18% of your 2024 earned income, whichever is lower. If you earned $60,000 in 2024, your limit is $10,800, not $32,490.

Put the amount you want to deduct on line 20800. Make sure it doesn't exceed your deduction room. Keep your receipts. That's it.