Re CAI 2021: Just give the the letter that comes with Profile.  It will give taxpayer a better estimate than last year's CAI. Also, only one spouse can receive credit in household. I ask CRA and they stated "whoever" gets processed first will receive the CAI,  which is more than last, when I completed Schedule 14 Ontario. However, it will show on both taxpayer & spouse returns, but does not show fully the calculations you see in Profile S14 when printed. 

Prepared of Ontario & Quebec tax returns

A. Pilon