Okay see attached.

I have moved the data to a Data worksheet and removed the Merged cells fom the table grid as merged cells are evil (use centre accross selectiion instead)

You will need to test the formula using filters on the Data sheet to make sure my logic is what you are expecting

Also the date periods you are using as 30 days mean that the periods will start to become strange over time (as month 12 is - 8th of May to 7th of June?). It is easy enough to have a calculation that always works out the real months with EOMONTH - see the date fields on my Grid

Attached Files

Caseload monitoring_ar12.xlsx (40.9 KB, 15 views)