Montana, on the other hand, isn't so technologically advanced. I browsed their tax instruction book online - and apparently all residents, non-residents, and part-year residents have to file. It sounds rather complicated for a part year resident:
As a part-year resident, you are subject to Montana tax on all your Montana source income included in your federal gross income which is received while residing in Montana and on all income which is derived from or connected with Montana. Complete lines 1 through 42 of Montana Form 2 using the instructions on pages 2-6 of this booklet. Report your Montana and non-Montana income as shown on your federal income tax return. Line 20 of Form 2 must agree with your federal adjusted gross income reported on your federal income tax return. You are allowed to claim either the standard deduction or itemized deductions and at least one personal exemption. Once you have completed Form 2 through line 42, you must complete Form 2A page 2, Schedules III and IV to prorate your Montana tax liability.While the forms are online, they're in a version of PDF that doesn't let me save what I enter. Argh!
So, I'm downloading and installing PDFCreator, which should let me print the edited PDF to another PDF. A bit silly, but hopefully it'll work, so all I have to do tomorrow is print it out and mail it.