In April, I used form 51 and the limited amount of information I had at the time to calculate the estimated tax payment for a client.  They sent in the amount (80% of estimate).  In October, when I filed the return, form 51, line 2 was changed to be the ACTUAL amount, not the estimated amount for tax due.  Therefore, the 80% was no longer accurate.  My clients now have a decent penalty.  I am concerned that the October version is what Idaho thinks we predicted back in April.  However, Idaho is a state that Proseries doesn't file the extension electronically.  I am not sure if client sent the entire form or if they just cut off the payment coupon.  Is this something we can argue Idaho over?  

In the future, I won't use the 80% of estimated method.  I will use 100% of prior year method.