Hi Kathi,

Thanks for your reply. 

Yes, I already talked with support and their answer was:

"development stated reason being is the amounts are hard-coded on the form with little instruction from the state"

The solution:

"At this time the option would be to override the amount on line 18 and paperfile as the actual interest percentage cannot be changed"

A couple of things about this issue:

1- Little instruction from the state: Not true at all. 502UP instructions gives the exact % to be used for late payments on the 4th period and how to calculate the interest based on the late payment date.

I know this because I had to manually calculate the penalty. It's not complicate but time consuming. 

2- MD won't accept an override on the 502 form which makes impossible to calculate or fix the wrong calculation. It could be avoided by either using the right calculation OR overriding the % on a different field that doesn't create the e-filing error.

Instead, I have to manually calculate the penalty AND PAPER FILED a return.

This solution defeats the purpose of using a tax professional software (not cheap by the way) and creates more issues for me, for example having to explain to my client that in the year 2025, he will have to print and mail a state return because the software cannot handle a simple math calculation.

I'm also surprise that this issue cannot be fix when the software can deal with more complex situation than a simple % penalty calculation.

Anyway, thanks for your reply.