Formula to subtract a $ value based on specific date

[Guest]

Can't seem to find the right formula string to subtract a $ value from a true
$ value based on a specific < or > "day" of the month - $ penalty charged
based on the "day" value is received.

 

[Pete_UK]

Tell us what your penalty rules are and give us some details about how
your data is laid out - where the "true" $ value is and where you want
to see the adjusted value etc.

Pete

 

[Don Guillett]

Pls clarify a bit with examples

 

[Guest]

Hello Pete and Don. I have a "loan amortization" worksheet that takes a
"payment" and breaks it down into "interest" and "principal". What I'm
trying to do is add a formula to the "payment" cell that will automatically
subtract a "late fee"; say $30 based on a "posted date"; date payment is
received and then breakdown the balance of the "payment" into interest and
principal. I tried to find a "pre-existing" spread sheet at MS with no luck.
While I have your attention, any suggestions on information site / books that
I could have referenced to find this information?? Thanks!!