Have you ever hit “submit” on your tax return, only to find a stray T slip in the mail the very next day? Or maybe you reviewed your return later and noticed a small error, like a missed RRSP contribution or incorrect rental or business income. These things happen. And when they do, panic often sets in. But the good news? Fixing a mistake after filing doesn’t have to be stressful or costly.
In this article, we’ll break down exactly what to do if you get a new tax document after filing or spot a mistake on your return. You’ll learn how to avoid penalties, fix errors the right way, and understand which method—CRA ReFILE or a T1 Adjustment—is right for your situation. Plus, we’ll show you how a CPA firm like Boyer & Boyer can take the pressure off with expert guidance.
Why Tax Slips Get Missed or Delayed in Canada (CRA Filing Issues)
Most Canadians aim to file on time and move on. But the tax system doesn’t always cooperate. Here are a few reasons why important slips may show up late:
- Delayed reporting by institutions: Investment firms, banks, and employers may issue tax slips closer to the March 1 deadline or later.
- Paper delivery problems: If you’ve moved or haven’t updated your address with all institutions, slips may go missing or arrive late.
- Online-only notices: Many slips are now delivered digitally, but Canadians often miss emails or forget to check online portals.
The most commonly forgotten tax slips include:
- T3s for trust and investment income
- T5s for interest and dividends
- RRSP contribution receipts (especially from early March)
- Amended T4s or corrected T4As
It’s easy to miss one or two of these, especially if you work multiple jobs, have freelance income, or invest through several platforms. But what happens if you do?
What Happens if You File a CRA Tax Return With a Mistake?
The CRA has sophisticated systems that automatically cross-check the slips they receive from employers and financial institutions with what you report. If there’s a mismatch, you could:
- Receive a Notice of Reassessment
- Owe additional tax, plus interest
- Face penalties if the mistake looks like neglect or misrepresentation
It doesn’t matter if the mistake was unintentional. The CRA expects accuracy and full disclosure. If you’re lucky, you’ll receive a letter giving you time to correct the issue. But waiting for the CRA to flag the problem usually results in more stress, and more money out of your pocket.
Acting quickly is your best defense. You can either refile your return using CRA’s ReFILE tool (if eligible), or submit a formal T1 Adjustment. We’ll walk you through both below.
How to Fix a CRA Tax Return After Filing in Canada
CRA ReFILE: How to Fix a Recent Tax Return
The CRA’s ReFILE system lets you correct certain returns online
However, ReFILE does come with limitations:
- You can’t use it for tax years before 2022
- It doesn’t support all types of changes (like address updates)
- Some complex adjustments still require a paper submission
If your tax situation qualifies, ReFILE is a great option. But when it doesn’t? You’ll need to file a T1 Adjustment.
T1 Adjustment: Fix Older or Complex CRA Tax Returns
A T1 Adjustment is the traditional way to correct older tax years or submit more complex changes. You can do this:
- Online using your CRA My Account
- By mail using the T1-ADJ form
You’ll need to:
- Specify the exact change
- Include supporting documents (e.g. new T4 or RRSP receipt)
- Wait for the CRA to process your request (4–8 weeks typically)
While slower than ReFILE, this method gives you more flexibility to correct issues like multiple year errors or newly discovered income.
Got a New T4 After Filing? How to Update Your CRA Tax Return
This is one of the most common reasons people need to refile or adjust their tax return. Here’s what to do if it happens to you:
- Confirm the slip wasn’t already included in your return.
- Evaluate whether the change is material. A small $5 T5 may not require action—but a T4 with $15,000 of income? That needs fixing.
- Choose your method: ReFILE if eligible, T1 Adjustment if not.
Still unsure? A CPA can help determine whether it’s worth the adjustment—and how to avoid raising red flags with the CRA.
Tax Slips That Require CRA ReFILE or T1 Adjustment
- A second T4 from a part-time job you forgot
- A corrected T4A from your pension plan
- A new RRSP contribution slip from early March
- Investment income that arrived electronically, but you didn’t see it
CRA ReFILE vs T1 Adjustment: Which Tax Fix is Right for You?
Both options serve the same purpose—correcting your return—but knowing which one to use matters.
| Feature | ReFILE | T1 Adjustment |
| Availability | Most recent 2 tax years | Any past year (as far back as needed) |
| Submission method | Online through tax software | Online or paper form |
| Supporting docs | Not always required | Often required |
| CRA processing time | Fast (days) | Slower (4–8 weeks) |
| Best for | Simple slip corrections | Complex or multiple changes |
If you’re unsure, a CPA can review your return and advise on the best method. ReFILE is great for straightforward updates. But if you’re juggling several documents or correcting older returns, the T1 Adjustment is your go-to.
Avoid CRA Penalties: Fix Tax Filing Mistakes Fast
The CRA doesn’t penalize honest mistakes—as long as you correct them promptly. Waiting to see if they notice your error can backfire, especially when interest compounds daily on balances owing.
Here’s what’s at stake:
- Daily interest on underpaid taxes, even from the original due date
- Late-filing penalties if the adjustment pushes your owed taxes higher
- Reputational risk if flagged for audit or review more than once
A fast, clean correction shows you’re acting in good faith. Even if the mistake is significant, the CRA tends to respond more favorably when you take initiative.
Not sure how to act fast? This is where professional help becomes valuable.
How a CPA Can Help Correct Your CRA Tax Return
Fixing your return isn’t just about punching numbers into a form. It’s about protecting your finances, avoiding red flags, and making sure the CRA doesn’t get the wrong idea.
Here’s how Boyer & Boyer, CPA, supports clients after tax season:
- Slip Review: We’ll double-check to ensure all documents are properly included in your filed return.
- Correction Strategy: We evaluate whether you should ReFILE, submit a T1 Adjustment, or do nothing at all.
- CRA Audit Defense: If your issue has triggered a CRA review, we’ll represent you and provide full compliance support.
Why go it alone? Our team handles post-filing issues every year—and knows how to work with the CRA so you don’t face unnecessary penalties.
⚠️ Worried About a Missed Tax Slip? Let Boyer & Boyer review your return and fix it fast—before penalties hit.
👉 Book Your CRA Correction Review Today
Final Tips: Fix CRA Tax Return Errors Before It’s Too Late
Tax season doesn’t end when you click “submit.” New slips and unexpected errors can pop up days or even weeks later. Acting quickly and choosing the right fix helps protect your return, your wallet, and your peace of mind.
Mistakes happen. Slips get missed. But what you do next matters most. Instead of guessing and risking penalties, get expert help.
Visit Boyer-Boyer.com to schedule a tax correction review today
