Not knowing how an extension works
If you’re running out of time with tax filing and need an extension, make sure you know how the extension process works. “If you file for an extension, you are supposed to send a payment for what you may possibly owe,” said Daniel Slagle, a certified financial planner who co-owns Fyooz Financial Planning with his wife. “If you don’t, you may owe additional penalties and interest.” So make sure you have all the money by April 15, even if you officially file in October.