Why Getting Your Tax Return Right Matters

Filing your Canadian tax return accurately isn't just about avoiding penalties — it's about making sure you receive every dollar you're entitled to. Mistakes can delay your refund, trigger a CRA review, or cause you to miss credits and deductions altogether. Here are ten of the most common errors and how to avoid them.

1. Filing Late (or Not Filing at All)

The standard deadline for most individuals is April 30. Self-employed individuals have until June 15 to file, but any balance owing is still due April 30. Filing late when you owe money results in interest charges and a late-filing penalty. Even if you can't pay, file on time to avoid the penalty.

2. Using the Wrong SIN or Personal Information

A simple typo in your Social Insurance Number or date of birth can cause your return to be rejected or delayed. Double-check all personal details before submitting.

3. Forgetting to Report All Income

All income must be reported — including freelance work, rental income, tips, foreign income, and investment earnings. The CRA receives T-slips directly from many employers and institutions, so unreported income is often flagged automatically.

4. Missing T-Slips

Wait until you've received all your T-slips (T4, T5, T3, T4A, etc.) before filing. Through CRA My Account, you can view slips submitted on your behalf — a useful way to make sure nothing is missing.

5. Not Claiming All Eligible Deductions

Many Canadians miss legitimate deductions such as:

  • Union or professional dues
  • Moving expenses (for eligible relocations)
  • Child care expenses
  • Employment expenses (if your employer completes Form T2200)

6. Forgetting Carry-Forward Amounts

Unused RRSP contribution room, capital loss carry-forwards, and unclaimed tuition credits from prior years can all be applied on this year's return. Your NOA from last year will show many of these balances.

7. Claiming Ineligible Expenses

On the flip side, claiming expenses you're not entitled to — like personal expenses as business deductions — is a serious issue. The CRA may request documentation for any claimed expenses and can reassess your return if something doesn't hold up.

8. Not Reporting a Spouse or Common-Law Partner

Your marital status affects several credits and benefits. If you have a spouse or common-law partner, you must report their net income on your return even if they had no income. Failing to do so can affect the accuracy of benefit calculations like the GST/HST credit and CCB.

9. Forgetting to Sign and Date (Paper Returns)

It sounds basic, but unsigned paper returns are returned unprocessed. If filing electronically, ensure you certify your return before submitting.

10. Not Keeping Supporting Documents

Even after filing, the CRA can request support for claims you've made — typically for up to six years. Keep receipts, T-slips, medical invoices, and other supporting documents organized and accessible.

Final Tip: Use Certified Software

Using CRA-certified tax software (many of which are free for simple returns) significantly reduces the risk of calculation errors and ensures you're guided through all applicable credits and deductions. The CRA maintains an updated list of certified software on its website each filing season.