Extend vs file and amend

[wdlevy]

I have an investment that always issues a K1 long after the filing deadline.  It never changes my taxes owed (but maybe gives me future deductions if I get the right kind of profit to offset). It will not change my amount owed.  I always extend then file once it arrives. Can I file now (and get my refunds) and amend when the K1 arrives?

[Mike9241]

sure. but if there's a surprise on the k-1 resulting in you owing taxes you will get hit with a 5% per month underpayment penalty.  

the issue is refunds.  say that you get a refund. but then owe $1000 on the amended return that you don't file until 10/15  6 months late payment at 5%  so you could owe the iRS an additional $300.

if you don't owe or are entitled to a larger refund no penalties.

however,  all this means if you file without extending you must pay in all the taxes you will owe by the original due date, then amend. with an extension you still have to pay in any taxes you'll owe by the original due date but then won't have to amend.