I submitted my profile for express entry as single / never married and got invite under CEC category. I'm planning to get in a month, how do I add my spouse to my IT?
If you have received the ITA, your profile gets locked in the system and you will need to write to IRCC to add your spouse to the application. However, if you add your spouse before you submit your application, it will lead to a re-calculation of your CRS points. If the recalculated score falls below the minimum score when the invite was issued to you, it could lead to a rejection. However, if you submit after e-APR, your CRS points do not get recalculated.
At this stage, it is your call when to add your spouse. Generally, if you add your spouse to the application after e-APR, IRCC will give you 30 days to gather all the documents for your spouse and submit it (the timelines will differ now because of COVID).
If you are not too worried of the decrease in points at this stage (Post-ITA), it is best to do add your spouse for ease of tracking, planning, and approval.
All the best!