Count Number of Days, In a rolling 12 month period

Gurus -

I have to count the number of days that someone is out of the country in an 12 month rolling period.

My data is a list of employee names, the dates that they departed and re-entered the country and that drives the total number of days out of country.
I have to keep a track of that travel and ensure that it does not breach 90 days in any 12 month rolling period.

Each time someone is out of country, there is a new row added.
I will need to measure multiple destinations too.

Appreciate any help - Bianca