Create a formula with date constraints

Could use some help with the following:

I created a spreadsheet to track payments made to contractors. In this spreadsheet I have a simple formula that tells when the payment has to be made based on the date it was rec'd from the contractor and adding on the payment terms.

Now what I have to do is add in some date constraints. Our paying office only processes payments between certain windows during the month. Lets say that for this month the payment window closes Jan 27th to Feb 2nd. What I need to do is if after someone enters the date the payment is rec'd and the 14 days is added for the payment terms, should the date the payment is made end up falling within the payment black-out period (Jan 27th to Feb 2nd), I then need excel to adjust the must be paid by date to 3 days prior to the black-out period.

Hope this makes sense....I've tried a whole bunch of different things and have looked online at several sites with no luck. Would SERIOUSLY appreciate it if someone can help me!

Thanks!