the broker will report the tax basis as what you originally paid because it does not get the K-1 info to adjust it. that's your responsibility. on the 1099-B the sale should be coded B or E to indicate the "tax basis" was not reported to the IRS by the broker. upon complete disposition and no wash sale, any losses are allowed in full. both those on the k-1 and any loss on the sale. a wash sale may be appropriate but that depends on whether you have an actual loss on the sale (this will differ from what the broker is reporting) and bought the same security in the wash sale period. you should have received a supplemental schedule from the MLP with the K-1 showing your adjusted cost basis to which you must add any 751 recapture reported on that schedule. that's your correct tax basis. so sales price vs this adjusted tax basis is what determines if you have a wash sale or not.
my notes on reporting disposition on MLP/PTP that does not involve a wash sale
Enter the k-1 info
Check the PTP box
If total disposition proceed as follows:
Check final K-1 (s/b marked on actual k-1)
Check sold or otherwise disposed of the entire interest
Use QuickZoom to get to the following section (maybe only available on desktop versions) but in online versions you should eventually get to a screen to enter this info.
On the k-1 disposition section for "sales price" only use the ordinary income (sometimes you’ll see a column with the “751” or the words “Gain subject to recapture as ordinary income”. This info comes from the supplemental sales schedule that should have been provided.
Cost is zero
Ordinary income is the "sales price".
This info flows to form 4797 line 10 and is taxed as ordinary income.
Now for the 8949.
enter the proceeds from the 1099-B. use the tax basis as described above. there is no need to enter an adjustment code.
Other
your qbi income /loss is what's reported in 20Z on the k-1. in addition the 751 recapture is QBI income.
