@dd4vols Are you sure about Kentucky?  They may not have received a 1040 extension, but 59 counties got other relief, including delayed ES payments which would affect any Form 2210 computation. 

How does IRS (or any software) know from the ZIP Code whether a taxpayer is a disaster victim?  If I have clients with a late filed return, can they move to Tennessee and avoid penalties?  Can I send them to you and ask if they can use your office address?  (That would avoid questions from state revenue departments, as well.)