Tax Deadline April 30: The Most Common CRA Mistakes Canadians Make — and How to Avoid Them
Missed deductions, wrong SINs, unreported side income — these are the errors that delay your refund, trigger CRA letters, and quietly cost Canadians millions every year. Here's your 2026 checklist
Whether you're a first-time filer, a seasoned DIY-er, or someone handing everything to an accountant, here are the 10 most common CRA mistakes Canadians make — and exactly how to avoid each one.
1. Misunderstanding the April 30 deadline
The filing deadline for most Canadians is April 30, 2026. Miss it when you owe money, and you'll face a late-filing penalty of 5% of the balance owing, plus an additional 1% per full month your return is late (up to 12 months). If you were penalized for late filing in a previous year, the rate doubles to 10% plus 2% per month.
No balance owing? There's no late-filing penalty — but filing on time is still strongly in your interest. It triggers payment of the GST/HST credit, Canada Child Benefit, and provincial credits that depend on an annual return being on file.
2. Not reporting all income
The CRA receives copies of most income slips directly from employers, financial institutions, and government agencies. If what you file doesn't match what they already have, expect a letter. The matching happens automatically, and it catches more people than you'd expect.
Income sources Canadians commonly forget to report:
- Freelance, contract, or side-gig earnings — including cash payments
- Rental income from a property, basement suite, or short-term rental (Airbnb, VRBO)
- Investment income: dividends, interest, and capital gains
- Government benefits: CERB repayments, employment insurance, maternity/parental benefits
- Foreign income — the CRA requires worldwide income reporting from Canadian residents
- Tips and gratuities
- Cryptocurrency transactions — the CRA treats crypto as a commodity; dispositions (selling, trading, or using crypto to buy something) are taxable events
3. Leaving deductions and credits on the table
Failing to claim what you're legally entitled to is one of the most quietly costly tax mistakes in Canada. Many Canadians simply don't know what's available to them.
Frequently missed deductions:
- RRSP contributions — the deadline was March 2, 2026, for the 2025 tax year
- Home office expenses — if you worked from home in 2025, you may qualify under the detailed method using Form T2200 from your employer
- Union dues and professional membership fees
- Moving expenses (if you relocated at least 40 km closer to a new job or school)
- Childcare expenses — daycare, after-school programs, eligible summer camps
- Carrying charges and interest on investment loans
- Employment expenses for tools, supplies, or vehicle use (Form T2200 required)
Frequently missed credits:
- Disability Tax Credit (DTC) — for yourself or a dependant; this one is often unclaimed because people don't realize they qualify
- Medical expenses — eligible costs include prescription drugs, dental work, eyeglasses, physiotherapy, and mental health therapy
- Charitable donation tax credit — donations above the first $200 are credited at the top marginal rate
- Tuition and education amounts (yours or transferred from an adult child)
- First Home Buyers' Tax Credit
- Canada Caregiver Credit
- Age amount (if you turned 65 or older in 2025)
- Ontario Trillium Benefit and other provincial credits
4. Errors on personal information
The CRA matches your return against its own records using identifiers you might assume are boring formalities. They're not — a single wrong digit can freeze your return in its tracks.
- Social Insurance Number (SIN) — one transposed digit causes a mismatch that can delay processing for weeks
- Your legal name and date of birth — must match CRA records exactly
- Direct deposit banking details — a wrong transit or account number means your refund goes nowhere, or worse, into the wrong account
- Marital status — changes must be reported, as they affect benefit calculations across the board
- Province of residence as of December 31 — this determines which provincial tax rates and credits apply to your entire return
5. Not reporting your spouse or common-law partner's income
If your spouse or common-law partner had little or no income in 2025, you may be able to claim the spouse or common-law partner amount, which can reduce your federal tax bill meaningfully. But you must report their net income on your return regardless.
Failing to include your partner's income affects the calculation of income-tested benefits — the GST/HST credit, Canada Child Benefit, and several provincial programs. The CRA will reassess you if the information is missing or wrong, and a reassessment rarely comes with good news.
6. Misreporting capital gains
Capital gains reporting trips up a lot of Canadians — and 2025 brought continued complexity following the federal government's proposal to raise the capital gains inclusion rate from one-half to two-thirds for annual gains above $250,000 (for individuals). The CRA expects accurate reporting regardless of the ongoing policy uncertainty.
Common capital gains errors include:
- Forgetting to report the sale of investments, a rental property, or a secondary residence
- Incorrectly calculating the adjusted cost base (ACB) — especially for mutual funds with reinvested distributions
- Not reporting the deemed disposition when assets are transferred to a family member or trust
- Failing to report foreign property dispositions — and not filing Form T1135 if your foreign assets exceeded $100,000 CAD at any point in the year
7. Getting your RRSP contributions wrong
RRSP errors are among the most financially damaging tax mistakes in Canada — and some of them come with monthly penalties.
- Over-contributing beyond your deduction limit results in a penalty tax of 1% per month on the excess amount
- Claiming the same contribution twice — once for 2025 and once for 2026 — is a common error for January–March contributions
- Forgetting to include contributions made to a spousal RRSP
- Not checking your actual deduction limit on your most recent Notice of Assessment before contributing
8. Not keeping receipts and records
You don't submit most receipts when you file — but the CRA can and does request them during reviews and audits, sometimes years later. The CRA can generally reassess a return for three years after the original assessment, and in cases involving misrepresentation or fraud, there is no limit.
Keep documentation for: all T-slips and income records, RRSP contribution receipts, medical expense receipts, official charitable donation receipts, business and home office expense logs, vehicle mileage logs, and property purchase and renovation records (essential for calculating capital gains down the road).
9. Filing on paper when NETFILE is available
The CRA processes electronic returns in as little as 8 business days — compared to up to 8 weeks for paper returns. If you're still filing by mail out of habit, it's time to reconsider.
Most Canadian tax software — TurboTax, H&R Block, Wealthsimple Tax, SimpleTax, UFile — is NETFILE-certified, and several options are free for simple returns. Electronic filing also significantly reduces the risk of arithmetic errors and transcription mistakes that paper filing invites.
10. Not filing because you think you owe nothing
This might be the most expensive mistake on the list. Hundreds of thousands of Canadians — particularly students, seniors, newcomers, and low-income earners — skip filing because they didn't work or didn't earn much. But not filing means the CRA can't issue the benefits that those Canadians are often most entitled to.
Filing a return, even with zero income, unlocks:
- GST/HST Credit
- Canada Child Benefit (CCB)
- Ontario Trillium Benefit and equivalent provincial credits
- RRSP contribution room accumulation
- Student loan interest claims and carryforward amounts
- Canada Learning Bond eligibility for children
Already filed and found a mistake? Here's what to do
Don't panic — and definitely don't file a second return. Instead, use the CRA's ReFILE service (available through most certified tax software) or submit a T1-ADJ (T1 Adjustment Request) form online through My Account or by mail.
If you're voluntarily correcting an error before the CRA contacts you, you may be able to reduce or avoid penalties through the Voluntary Disclosures Program (VDP). The key word is "voluntary" — the CRA must not have already started an audit or review related to the issue.
Final checklist before you hit submit
- All T4, T4A, T3, T5, and other slips collected and reviewed
- RRSP contributions reported correctly — no duplication, no over-contribution
- Spouse or common-law partner's income included
- All income sources declared, including side income, rental income, and foreign income
- All eligible deductions and credits claimed — nothing left on the table
- SIN, legal name, date of birth, and marital status verified
- Direct deposit banking information confirmed
- Capital gains calculated and reported accurately
- Receipts and supporting documents saved and organized
- Return submitted via NETFILE on or before April 30
This article is for general informational purposes only and does not constitute tax, legal, or financial advice. Tax situations vary. Consult a qualified tax professional or the Canada Revenue Agency directly for advice specific to your circumstances. MoneySavings.ca / Canadian Money Brief — moneysavings.ca/canadian-money-brief — Updated April 2026
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