Sum based on dates

Hi there,

I have created a large spreadsheet and I was wondering if it was possible to create a formula where the value of a cell updates automatically based on the date.

To make it easier to understand, the spreadsheet calculates a score for fighters in MMA and I want to deduct a certain number for every month since their last fight. I.e an inactivity score.

So I have a date next to each fighter and I want a cell to automatically update the score based on the date.

I doubt this is even possible but I am desperate for some help and would appreciate some advice, even if it means considering different software.

I use Excel 2016.

Many thanks,