If you owed additional tax then that tax was due on the due date for that years tax return extension or not 0 the extension is only an extension to *file*, not to pay so penalties and interest started on the due date of the tax return. If you owed tax and *did* pay then there could be an additional failure to file penalty.
If you were due a refund then the only penalty is that the government has your money and not you.
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**
