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Did you forget to file something or do you need to make changes for your tax assessment?

The due dates for the individual taxpayers’ pre-completed tax return this spring were either 2 April, 7 May, 14 May or 21 May 2024.

If you forgot to include income details or deductions in your tax return, or if you notice something in your tax assessment that needs to be changed, do this:



You can see the end date of your tax assessment on your tax decision or in MyTax. This date affects how you should report changes to your tax assessment. 

How to find your tax decision in MyTax

Where can I find the end date of my tax assessment?



If the end date of your tax assessment has not yet passed, you can make changes and additions to your tax return:

  • If you find an obvious error in the tax decision (such as a mistake in a mathematical calculation, etc.), call our service number stated on the decision. That way, we can correct the error before your tax assessment ends.
  • If you notice that any income items or deductions are missing from your tax decision, you can add or correct the information on your Pre-completed tax return in MyTax, or on paper, before the end date of your tax assessment.

The pre-completed tax return in MyTax — how can I make corrections to it?

Instructions for filing

How to file on paper


If the end date of assessment has already passed, you can claim adjustment

If the end date of your assessment has passed, you can request changes to your tax assessment by filing a claim for adjustment.

We recommend that if anything needs changing, the primary way to remedy the errors would be to act before the date when the Tax Administration finishes your assessment for the year. Add or correct the information on your Pre-completed tax return. This way, the Tax Administration can record your input faster.

If you did not have time to do that before the end date, you can send a claim of adjustment to the Adjustment Board. See the processing time of these claims.

See the instructions for filing a claim for adjustment

Please note that if you file details late, you may have to pay a late-filing penalty or a punitive tax increase. Read more about the late-filing penalty and the punitive tax increase.

Page last updated 5/22/2024