oil fund final K1 and related 1099B

[tax1111]

TP received 1099B which contains a sale of Proshare ultra bloomberg crude oil fund shares. The basis of the sale is the original purchase prices which is illustrated on the final k1 from Proshare ultra bloomberg fund TP received. The final k1 shows substantial amount of short term capital gains and 1256 income.
Based on my understanding, the cost basis of 1099B is wrong which does not reflect the cumulative basis adjustment which TP has already reflected in his personal income return each year through k1 data input.
So, I need to manually adjust the 1099B basis by the cumulative basis adjustment. Is my understanding correct?
Also, TP said he never receive any k1 for previous years except the final k1. How should I deal with this also? Ask him to contact Proshare fund asking for previous years' k1s and amend each impacted tax return?
Thanks.

[Randall]

Doesn't the K-1 come with some additional pages and supplemental info?  My experience has been these pages and instructions walk you thru what to use as basis and where to report different numbers.

[JRS]

On 4/3/2022 at 10:57 AM, tax1111 said:

Also, TP said he never receive any k1 for previous years except the final k1.

I don't see how he could complete his previous returns without a k-1.  All PTP's I have ever seen come with complete instructions and a "map" showing where each figure goes on the tax form.

[Abby Normal]

On 4/3/2022 at 1:57 PM, tax1111 said:

So, I need to manually adjust the 1099B basis by the cumulative basis adjustment. Is my understanding correct?

Yes, use adjustment code B for basis adjustment for the cumulative adjustments to basis in the K1 notes.

And use code O for the 4797 portion of the gain, then put the gain on the 4797 part II. There's a dropdown box to choose the K1 that it comes from.

The B adjustment is a minus and the O adjustment is a plus, so just net the two into one adjustment amount with the code BO (because these investments stink!)

And mark the K1 final and complete disposition of a PTP. This will release all of the suspended losses for that K1.