Looking for advice on calculating the total cost per month when using a w.c column

Hi all,

I’m pulling my hair out because I’m so stuck with this. Countless googles, YouTube searches and copilot suggestions and I’m still not getting what I need.

In excel I have the following columns in a table called “tbl_DataInput’

The column is on the left of the “-“ and the purpose is on the right.

W.C. date - the start of the week that someone inputs, I.e. 01/01/26

Days worked (1, 2, etc) - the number of days worked that week, I.e. 2

Name - persons name

Project Name - project name

Project - project category

Project No. - project number

Rate Number - rate card number

STD Hourly Rate - hourly rate

STD Daily Rate - daily rate

Rate for Week -combined rate for the amount of days worked

Rate for week helper - takes the rate for week but trims the £

Month, Year - the date at the start of the month for the invoice

Project No. 2 - the lookup reference to match with project no.

Invoice No.- invoice number

Predicted invoice cost - as it says

Actual Invoice cost - the sum of all of the dates that match the month (I.e. January) and the project number totalled

Match? - whether the predicted cost and the actual cost match

How do I create a formula that works out the actual invoice number by scanning the table and matching those that are in January to sum but, if the week starts at the end of the month, and for example only 2 days of that week are in January and the rest in February, it would only total January.

I hope that makes sense? I’m really stuck so any guidance would be appreciated.