Small Mistakes, Big Consequences
Tax season can feel rushed, especially when you're trying to file quickly to get your refund. But a few common errors can slow down your return, trigger unwanted CRA attention, or cause you to miss out on money you're entitled to. Here are the most frequent mistakes Canadians make — and exactly how to avoid them.
Mistake 1: Forgetting to Report All Income
All income must be reported — not just your main job. This includes:
- Income from a side job or freelance work
- Interest earned on savings accounts (T5 slips)
- Investment dividends
- Rental income
- Selling investments (capital gains)
- Government benefits such as EI or CERB-type programs
The CRA receives information from employers, banks, and benefit programs. If your return doesn't match what they have on file, expect a reassessment — and possibly penalties.
Mistake 2: Missing the Deadline (or Misunderstanding It)
The standard deadline for most Canadians is April 30. Self-employed individuals have until June 15, but taxes owing are still due April 30. Filing late when you owe money triggers a late-filing penalty of 5% of the balance owing, plus 1% per month for up to 12 months. Even if you can't pay, file on time to avoid the penalty.
Mistake 3: Not Claiming All Available Credits and Deductions
Many Canadians file quickly and forget to claim credits they're entitled to. Common ones that get missed include:
- Medical expenses (many more items are eligible than people realize)
- Charitable donations
- Union and professional dues
- Canada Workers Benefit
- Disability Tax Credit (for those who qualify)
- Public transit amounts (where applicable)
Take the time to work through the deductions and credits section of your tax software carefully — it often asks probing questions designed to catch things you might otherwise overlook.
Mistake 4: Entering the Wrong Social Insurance Number
This sounds obvious, but typos in your SIN are more common than you'd think, especially when filling out forms quickly. A mismatched SIN can cause the CRA to flag your return and delay processing. Double-check this field before submitting.
Mistake 5: Not Carrying Forward Unused Credits
Some credits don't expire — they carry forward to future years. The most important ones to track are:
- Tuition credits — Unused amounts carry forward indefinitely.
- Capital losses — Net capital losses can be carried back three years or forward indefinitely to offset capital gains.
- RRSP contribution room — Unused room accumulates every year.
Your most recent Notice of Assessment is the best reference for your available carryforward amounts.
Mistake 6: Throwing Away Receipts
When you file electronically, you don't submit your receipts — but the CRA can request them at any time for up to six years after you file. Failing to produce receipts when asked can result in the CRA disallowing your deductions and reassessing your return. Keep digital or paper copies of all supporting documents.
Mistake 7: Not Updating Your Direct Deposit Information
If you've changed banks or closed an account since your last filing, your refund may be sent to an account that no longer exists. This creates a delay while the payment is returned to the CRA and reissued by cheque. Update your direct deposit information through CRA My Account before filing.
A Quick Pre-Submission Checklist
- Have you reported all income sources?
- Is your SIN entered correctly?
- Have you claimed all applicable deductions and credits?
- Have you entered any carryforward amounts from previous years?
- Is your direct deposit information current?
- Have you saved copies of all receipts?
- Did you review the software's error-checking summary before hitting submit?
When to Use the CRA's ReFILE Service
If you realize you made a mistake after filing, don't panic. You can use the CRA's ReFILE service through your tax software to electronically submit an amended return for the current and previous tax years. This is faster than mailing a T1-ADJ form.
Bottom Line
Taking an extra 15–20 minutes to review your return carefully before submitting can save you weeks of delays — and potentially hundreds of dollars. Accuracy and completeness are just as important as speed when it comes to getting your refund quickly.