Does it matter where I mail a prior year return from? As long as its post marked for today is that correct? And a place like mailbox inc should be ok to mail from?

[dmartin15nitramd · Accepted solution]

You can mail it from any US post office as long as the post mark date is correct. 

Non USPS sites may not be collected in time, so be sure to verify collection time, or go to your nearest post office.

[JulieR]

If you are filing a prior year return, the post mark is irrelevant since the return is already beyond it's due date.

[neu-ham]

What about the 3 year mark if expecting a return?

[JulieR]

Yes, if you're expecting a refund, you'd have until 04/15/2019 to file a 2015 return.

[neu-ham]

I wonder... The deadline for 2015 was 4/18/2015 do you think that means I will have till 4/18/2019 to file?