If it helps at all, my US taxes were about 3 months late a couple of years ago, with no extension, through no fault of my own, and I was panicking about it. I was fined for the late return - but it turned out to be something like $3.00 a month... I imagine it would be worse if someone did it regularly, but I'm sure it'll be okay! Stoopid taxes. Bizarrely enough they sent me tax papers this year even though I've not been in the US for two years now... I presume I don't have to do anything! Eep!