Did My Accountant Miss Anything?
The credits most often missed on Canadian returns, how to check past years without starting a fight, and how to claim what was missed up to 10 years back.
The short version
- Preparers miss things mostly because nobody told them: the medical receipts in the drawer, the parent who moved in, the tuition from three years ago.
- The most-missed items are credits and carry-forwards, not exotic deductions.
- CRA accepts corrections for the previous ten calendar years, so a miss from 2019 can still be fixed.
- Check past years with Refund Finder and this year's return before it's filed with Return Check.
- If something turns up, take it to your preparer first. Most will fix it at no charge.
Did My Accountant Miss Anything?
Every tax preparer works from what's in the envelope you hand them. If the envelope has your T4s and nothing else, they'll file a perfectly correct return that's missing the $2,400 of dental work, the union dues and your mother's caregiver amount. That isn't negligence. It's the same reason a mechanic can't fix the noise you forgot to mention.
So the useful question isn't “did my accountant mess up?” It's “did anyone ever see everything?” Usually, the honest answer is no.
What Gets Missed Most
- Medical expenses. Especially for a spouse, children or a dependent parent, and especially when picking a different 12-month period would get more of them over the threshold.
- Credits for age, pensions and disability. The pension income amount, pension splitting with a spouse, the disability amount for someone already approved, and the caregiver amount.
- Carry-forwards. Unused tuition, capital losses, RRSP contributions that weren't deducted, and donations, which can wait up to five years and be pooled between spouses.
- Slips with tax withheld. A T4A or a T4RSP entered without its tax-deducted box. That's your own money.
- Claims on the wrong spouse. Medical usually belongs on the lower-income return, child care almost always does.
- One-off credits. The home buyers' amount, the home accessibility expense credit, the multigenerational home renovation credit and the Canada workers benefit.
Did you (or your accountant) miss anything?
Refund Finder reads your last three returns and lists the credits and deductions you missed, with the value of each and how to claim it. Under $100 found, your fee back.
How to Check Without Starting a Fight
- Pull your notices of assessment and the returns as filed from My Account. CRA keeps them there.
- Run them through Refund Finder, or go line by line with our tax credits and deductions guides.
- Take what you find, with the receipts, to whoever did the return. Lead with “I found these receipts I never gave you”, not “you missed this”. Most preparers will file the correction for free, and you keep a good relationship with someone who knows your file.
- If you did the return yourself, change it in My Account with “Change my return”, or mail form T1-ADJ. See how to change your return.
When It Really Was a Mistake
Sometimes it was: a slip typed wrong, a credit skipped that was on the paperwork you provided. A professional who made the error will usually fix it and absorb the cost. If a mistake caused penalties or interest, ask the preparer about it before anything else; CRA's relief program generally doesn't accept “my preparer made a mistake” as a reason on its own. For a large or disputed amount, our help finder points to the right kind of professional.
Check this year before it is filed
Return Check reads the return your preparer or software produced, with your slips, and lists what to fix and what's missing before it goes to CRA.
Questions About Missed Claims
Can I claim something my accountant missed on a previous return?
Yes. CRA accepts requests to change a return for the previous 10 calendar years. Your preparer can file the change, or you can use Change my return in My Account or form T1-ADJ.
What are the most commonly missed tax credits in Canada?
Medical expenses (especially for family members), the pension income and age amounts, disability and caregiver amounts, unused tuition and other carry-forwards, donations, union dues, the home buyers’ amount and the Canada workers benefit.
Will my accountant charge to fix a missed claim?
Many do not, especially when it was their error. When the missed item came from receipts you never provided, some charge a small fee for the adjustment. Ask first.
Can CRA penalize me for claiming something late?
No. Asking CRA to change a return to claim a credit you were entitled to is normal. Keep the receipts in case CRA asks for them.
Sources: CRA, Form T1-ADJ; CRA, Lines 33099 and 33199, medical expenses; CRA, Line 34900, donations and gifts. Checked October 2026. Not tax advice. CanadianTaxes.ai is not the Canada Revenue Agency.
Last reviewed October 5, 2026 against CRA and Government of Canada sources. How we check our facts.