[BillinghamJ]

Google Sheets can do that - https://officewheel.com/group-dates-in-pivot-table-google-sh...

[smusamashah]

This is the text book answer. Not something you can actually do on a live sheet with all transactions. If you want to use a different aggregate e.g. week instead of month or skip first year or something like that you will be making these columns all over again.