I have no idea, but I'm assuming I'll have to pay some. I'm just going to file an extension and worry about it this summer.
You know, I looked into an extension last year. From what I read they still expected an estimated payment by the 17th, you just didn't have to have all of your finalized paperwork in until the extension date. You might want to look into that, and then let me know if you find out something differently so I can file an extension this year too.
Last year, we paid $20 when we filed the extension for my wife (fiancee at the time). We actually got another extension until 10/15 and she ended up owing $645 according to Turbo Tax so that's what we paid. We got a letter from the IRS a couple weeks later saying we owed ~$19 in interest. That was it.
Refund of $2400...which is pretty much all gone already from a couch we bought in January and dental bills.
Got a refund back of $2400.00 that goes right into my savings. To be honest with you, I don't know how the hell to do taxes so I let my dad did them for me for free, who is an H&R Block certified...thank you dad!