I had never traded futures right up to the last business day of the year, but I did so in 2016. From what I can gather, unlike Canadian stocks which are T+3 and thus needed to be traded on the 23rd of December to be accounted for in 2016, it appears that US futures settle same day they are traded.

Now, from what I can gather:

Dec 27th, 2016 - final trade date for US equities for settlement in 2016 tax year.
Dec 29th, 2016 - final trade date for Options for settlement in 2016 tax year.

What I have been unable to locate is what the final trade date is for US futures. And, Interactive Brokers is notoriously poor with their tax forms so I can never trust what they put down.

Thus, I don't actually know what date I should use for US futures settlement with respect to taxation as all my research doesn't mention futures specifically. And, because Options are considered a separate entity, I wonder if futures are, too.

Does anyone have a source that spells this out?