Let’s assume you are a domestic taxpayer, and you received a K-1 with box 16 checked for a partnership that is also only domestic. if you do have foreign components this may still help, but I’m answering for domestic.
Partnerships have to provide that info, because they don’t always know if the taxpayer needs that info for their own foreign filing. The info they provide is voluminous, and doesn’t match up with any of the line numbers on the K-3 worksheet form, and trying to find it online is like searching for “what fruit and vegetables can I bring into Canada).
The answer turns out to be simple, and it took me a bit to find it. Go to the K-1 line 16 worksheet (right under where you checked (K-3 attached), and right click on line B (Gross income from all sources). The pop up will tell you for each line B through R exactly where on the K-3 to find the information. If your sources are all US, most likely all you will need is line B entered to make the red box on Line 16 go away. But check the other entries on your own K-3 to be certain.
You leave line A blank if the entity is US, there is no US option on the drop down menu.
