Get your taxes done using TurboTax

sometimes the simplest thing is to go to the IRS website (or state for state forms) and read the instructions for that line.

from IRS instructions

 Specific Instructions
Part I
Line 1
Include on line 1 all capital gains and
losses from section 1256 contracts open
at the end of your tax year or closed out
during the year. If you received a Form
1099-B, Proceeds From Broker and
Barter Exchange Transactions, or
substitute statement, include on line 1
the amount from box 11 of each form. In
column (a), write “Form 1099-B” and the 

broker’s name. List separately each
transaction for which you didn’t receive
a Form 1099-B or substitute statement,
or received a Form 1099-B that isn’t for
your tax year.

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Turbotax has it backwards so the broker in the first column and 1099-B in the second.

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are you really making a 1256 loss election which involves calculating the allowable amount that can be carried back and then amending the 3rd prior year and possibly the 2nd and then the first prior year return for the allowed carryback.

the calculation is also described in the instructions. Here it is:

Box D. Net Section 1256 Contracts Loss Election
If you have a net section 1256 contracts loss for 2022, you can elect to carry it back 3 years. Your net section 1256 contracts loss is the smaller of:
• The excess of your losses from section 1256 contracts over the total of {(a) your gains from section 1256 contracts plus (b) $3,000 ($1,500 if married filing separately),} - (b) is inconsistent with code section 1212 dealing with 1256 loss carryback and PUB 550

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PUB 550

Net section 1256 contracts loss. This loss is the lesser of:
• The net capital loss for your tax year deter-mined by taking into account only the gains and losses from section 1256 contracts, or
• The capital loss carryover to the next tax year determined without this election

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or
 + The total you would figure as your short-term and long-term capital loss carryovers to 2023 if line 6 of Form 6781 were zero. Use a separate Schedule D (Form 1040) and Capital Loss Carryover Worksheet (in Pub. 550) to figure this amount.
The amount you can carry back to any prior year is limited to the smaller of:
• The gain, if any, that you would report on line 16 of Schedule D (Form 1040) for that carryback year if only gains and losses from section 1256 contracts were taken into account; or
• The gain, if any, reported on line 16 of Schedule D (Form 1040) for that carryback year.
The amounts just described are figured prior to any carryback from the loss year. Also, the carryback is allowed only to the extent it doesn’t increase or produce a net operating loss for the carryback year. The loss is carried to the earliest year first.
Make the election by checking box D and entering the amount to be carried back on line 6. To carry your loss back, file Form 1045, Application for Tentative Refund, or an amended return. Attach an amended Form 6781 and an amended Schedule D (Form 1040) for the applicable years.
On the amended Forms 6781 for the years to which the loss is carried back, report the carryback on line 1 of that year’s amended Form 6781. Enter “Net section 1256 contracts loss carried back from” and the tax year in column (a), and enter the amount of the loss carried back in column (b).