What counts as postmark date? if i buy postage on usps a day before and get it scanned does that count? Or does the postmaster need to actually stamp my package?
IF you are going to file by mail...
The postmark is the actual cancellation mark the PO puts on a letter. That contains the date.
BUT...to it gets dated properly, you should sue a tracking method when you mail....by actually filling out a Certified Mail form, and giving to the Service person at the PO counter. Costs a bit more, but it ensures the date is recorded.
Something dumped in a PO mailing box does not always get marked with the mailing date. Some PO's have notices posted as to exactly what time on the 15th they will ensure that your letter gets postmarked properly if you drop it in their mail slot...usually sometime around 4-6PM. But Certified mail is safer.
And remember Federal and State tax forms go to entirely different addresses...in separate envelopes.