Ok, missed Tax Day - how much am I going to owe in penalties?

Grudun answered 8 months ago …

I looked it up and if you owe taxes here is what I found:
If you have extended your return and didn't pay at least 100 percent of the tax you owe by April 15, you'll end up owing a late payment penalty of 0.5 percent per month until the tax is paid. The maximum late payment penalty is 25 percent of the amount due. You'll also owe interest on whatever amount you didn't pay by April 15. The rate being charged by the IRS in the fourth quarter of 2007 was 8 percent.

If you didn't get an extension and still owe a balance due you are looking at a late filing penalty of 5 percent of the unpaid tax per year plus interest. The maximum late filing penalty is 25 percent of amount due.

So you are looking at a 5.5% penalty on the upaid amount right now but it will go up every month. So far I haven't found out how this would reduce a refund.