1. Missing Eligible Deductions and Credits

One of the most common mistakes is leaving money on the table. Many DIY filers overlook deductions like moving expenses, medical costs, or employment expenses. Others miss out on tax credits such as tuition, Canada caregiver credit, or disability tax credit. Not claiming these can mean paying more tax than you need to.
 

Tip: Keep receipts throughout the year and review CRA’s full list of credits and deductions before submitting.

2. Reporting Income Incorrectly

DIY filers sometimes forget to include income from all sources—such as freelance work, investments, or rental properties. The CRA receives slips directly from employers, banks, and institutions, so missing income can trigger an audit or penalty.
 

Tip: Always check your CRA “My Account” to make sure all T-slips match what you report.

3. Claiming Ineligible Expenses

On the other side, some filers mistakenly claim expenses that aren’t allowed. For example, trying to deduct clothing, groceries, or personal vehicle costs as work-related when they don’t qualify. This can raise red flags and result in reassessments with interest or penalties.
 

Tip: Learn the CRA’s rules about what is deductible. If it feels like a stretch, it probably won’t qualify.

4. Incorrectly Claiming Dependants

Many DIY returns get complicated when it comes to dependants. Claiming a spouse, parent, or child incorrectly can delay your return or lead to rejected claims. For instance, the “eligible dependant” credit is only available in very specific situations.
 

Tip: Double-check eligibility rules before claiming any dependant-related credits.

5. Simple Math and Filing Errors

It sounds basic, but mistakes like typos, forgetting to sign forms, or entering the wrong RRSP contribution limit can delay your refund. Online tax software reduces some of these risks, but human error can still slip in.
 

Tip: Review your return carefully before submitting. A second look can save you weeks of processing time.

Final Thoughts

DIY tax filing isn’t a bad idea—if your financial situation is simple and you’re confident in your knowledge. But once your taxes involve multiple income sources, dependants, or deductions, a professional can help maximize your return and give you peace of mind.
 

👉 At FILETAXHERE, we specialize in helping Canadians—newcomers, families, and workers—file correctly, on time, and with the best possible refund. Don’t let a simple mistake cost you money.