As per CRA,
You can request a change to your tax return by amending specific line(s) of your return. Do not file another return for that year, unless the return you want to amend was a 152(7) factual assessment.
Wait until you receive your notice of assessment before asking for changes.
Generally, you can only request a change to a return for a tax year ending in any of the 10 previous calendar years. For example, a request made in 2021 must relate to the 2011 or a later tax year to be considered.
To ReFile your 2020 tax return please follow these links for detailed instructions:
Thank you for using TurboTax.
Yes, you might be able to make any corrections to your previous returns, using TurboTax, and then remit using the ReFILE option. You can make changes to your current and previous 2 tax years through Re-FILE. You cannot use ReFILE in the following situations:
- Making or amending an election
- Applying for certain benefits
- Applying for the disability tax credit
- Have a current reassessment in progress
- Have not yet received the original return assessment
- If you have to change personal information
Processing time could take up to within 2 weeks when done online and processing might slightly be longer if your request needs further review, or if the CRA has to contact you for more information or documentation.
For more information on ReFILE, see the link below: