Month Completion formula only if filtered month is equal to current month

Hi Everyone.

So I have a problem and think I have a solution, but not sure if it is possible

I have a measure built in to show me how far the current month is completed and shows me a perc

MonthCompletion = CALCULATE( DAY(TODAY()-1)/30)

I use this in the targets for each month to keep it Linearised against the Actuals

My problem now is that when I filter for prev months the Target KPI is multiplaying by a perc of the current month completion

Linearised Booking Target = dim_budget[Target Bookings]*[MonthCompletion]

So my question is,.. Is there a way where I can write an If statement in to change the month completion formula to show 1 or 100% when filtered month is not equal to Month(Now())

Thanks in Advance

Arnoux