If you received an extension to file your individual tax return,
the last date to file timely is October 15. SEPs and 401(k)s
must be funded by the filing deadline of your tax return, so if
you filed a schedule C and claimed a 401(k) or SEP deduction
it needs to be funded by next Thursday. If you have not funded
it yet, you should act right away to make sure your contribution
is processed on time.