Inseting fomula for column headings

Good Morning friends

Apropos the title, i have attached a sheet.

Every time, i have to calculate the same for each and every customer (here i have shown for customer D)
I want column titles viz Delay in days and Penalty to suppot a formula.

I have developed one( incomplete) for Delay in days for year2013, considering 14th (Sunday) for April and July

=IF(MONTH(E7)=OR(4,7),IF(DAY(E3)<=15,0,DAY(E3)-15...

not getting it for after 15th payments ?