# Excel Subtracting periods from specific dates using 360-day calendar?

Got formulas for figuring my differences between date periods in days as follows:

=IF(F7="","0",DAYS360(F6,F7)+1)

This gives the days result for each period that I am interested in, but I then need to add each period of days together and subtract them from a current date (like doing service computation). The issue is that I need to do this second calculation within a 360-day calendar as well. If I just try to do a days360() formula with one value being the current date and the other being the total number of days that I need to backtrack, then the "original" date that it comes up with is drastically off.

This seems to be the equivalent of the difference between NETWORKDAYS and WORKDAY functions. The former counts working days between two dates, the latter adds working days to a date, you essentially want the WORKDAY equivalent for DAYS360, which I don't think exists.

You can manipulate DAYS360, though, e.g. with a date in A2 and number of days to subtract (in 360 day mode) in B2 you can use this formula for the date

=A2-B2-MATCH(B2,INDEX(DAYS360(A2-B2-ROW(INDIRECT("1:"&CEILING(B2/30,1))),A2),0),0)