tsql – How to increase the counter based on the date selection

I have a table (checkBounce) with a column like: Accountid, Accountname, Chdate, chno, chamount
Now, I am creating a query that results in the Accountid count in a month.
Now I need to increase the count of the current month of Accountid with the value of the previous month based on the date selected by the user.
Can someone guide?