Can i file my 2020 tax return even after the re-assessment or should i submit the T2125 and t4A adjustment and send to CRA cz they need proof of expense.

Thank you for your question. Once you've filed your return (mistakes and all), you can't file a new one. But you can correct the original by way of an adjustment. You must wait until you have received your Notice of Assessment before submitting any adjustment requests.  

For more information, please see our article  How to Change Your Tax Return AFTER You've Filed

Thank you for choosing TurboTax .