for some taxpayers there will be nothing on the k-3 for them to report. for others reporting would be most likely when there is foreign tax credits involved (line 21 1065) . also reporting would likely be required for partnerships with foreign sourced income. investments in passive foreign investment companies (PFIC) and certain other situations.
extending is easy but you have to pay your taxes by 4/18. then file when you get it. I think this is easier than filing and then having to amend if reporting is necessary.
