How do i refile to include RRSP contributions for previous years back to 2018

[TurboTaxBrenda1]

As per TaxTips: you will log into CRA "My Account", if it shows a link to your most recent assessment on the Overview page, you can select the Change my return icon in order to make a change.  For a prior year, click on

Go to Tax returns details, then

Click on the Status of return (Assessed or Reassessed) for the year you want to revise.

Once at the assessment page, go to the bottom of the page and click on the Change this return icon.

You will be prompted for the line number that you wish to change on your tax return.

If you are trying to correct a prior return because you didn't enter all your RRSP contributions,

If you made RRSP contributions from March 3, 2020 to March 1, 2021, this should have been included on Schedule 7 which was filed with your 2020 tax return.  If you omitted any of the RRSP contributions during that period from Schedule 7, you will have to file an adjustment to your 2020 tax return.  You should be able to file a T1Adj online without submitting receipts, and if Canada Revenue Agency wants to see copies of the receipts they will request them from you.  If you only want to record the contributions, and not claim a higher RRSP deduction, you will be requesting a change to line 24500 (line 245 prior to 2019) of Schedule 7.  This is the line for total contributions made from March 3, 2020 to March 1, 2021, or the equivalent period if you are doing years prior to 2020.  If you are doing this online in "My Account", just search for the phrase schedule 7 when you get to the page that asks you to "Enter text or line number, or select a section."  This will bring up the lines available to be changed from Schedule 7.

Thank you for choosing TurboTax.