@Kauaiboy you just have to know where to look for instructions. schedule A of 1045 is not required because you can not create or increase an NOL when you carryback at 1256 net loss. there is no requirement to use form 1045. it's preferred if more than one year is involved. form 1040-X for 2019 will serve just as well if the carryback will all be utilized in 2019 and there is no effect on 2020 (see warning below) .
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from the FORM 6781 instructions
Make the election by checking box D (on form 6781 for 2022) 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).
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here's from the instructions for 1040-X
Loss or credit carryback. File either Form 1040-X or Form
1045 to apply for a refund based on either an overpayment of tax
due to a claim of right adjustment under section 1341(b)(1) or
the carryback of a net operating loss (but see Net operating
losses below), a foreign tax credit, an unused general business
credit, or a net section 1256 contracts loss.
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warning. while the instructions only mention form 6781 and schedule D in fact you must attach all forms and schedules that change that affect the revised tax figure. For example, if charitable contributions were near the limit for 2019 the c/b would reduce the allowable amount. this then would result in a contribution carryover so you would have to carry the disallowed amount forward to 2020 (or forgo any benefit). in such a case use of the 1045 is preferred. if you paid AMT and/or NIIT taxes those would likely change. an AMT change could affect the carryforward to 2020 and so on. a change in the NIIT tax would not affect any other years.
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the only reason to use 1045 is when multiple years are involved is that all the years and attachments go with 1 form rather than multiple 1040-Xs. With those there no guarantee that 2019 would be processed before 2020 even if you mailed them together. this could result in processing delays and even correspondence from the IRS. as a trick you could use Turbotax to prepare a 1040-X for each year involved. Carefully transfer the numbers to the 1045 and keep the X's for your records.
