I am late filing my 2007 Pa state taxes.How do I find out what the penalty is so that I know how much I need to pay.

Calculate the PA taxes.

If you have a refund coming, there will be NO penalty as there is NO late payment of taxes.

If you owe, file the return and pay the taxes. The state of Pennsylvania will BILL you for the late penalty and interest. You can then ask for a waiver of the penalties.