What is the best practice to report a change in marital status? If the client has been filing as separated for the last couple of years and now they are back together in 2018, do they have to file RC65 or simply change the status on T1-General?
Yes. File RC65 twice.
Once with date of separation effective date of separation.
Second time with date together (married or common-law). Check rules for effective date of change back to married or common-law. Be ready to substantial separate addresses with at 3 eligible documents.