First get into Forms mode (this means you're using the desktop program, not Online).
Then open Schedule C Give it a name (Trader)
Set Line 7 Accounting Method Other (MTM) [[or as you wish]]
Click the upper Quickzoom button Disposition Worksheet
Give it a description ( "Trading outcome")
In Part 1 A. enter (as per IRS instructions) "Trader-see attached".
The red boxes for Property A will open.
Fill in the red boxes with your tax year results.
For Type of property Choose H ( Ordinary ) [[or as you wish]]
Your 4797 p1 will be generated.
Open your form 4797 and complete Line 1 (one of the few fields that will take more than 10^7 dollars)
Open Form 1040 Click Print on the bottom of the screen.
The income appears on your Form 1040 Line 8 [[ Now Schedule 1 Line 4]]
Note: When the tax return is printed, Schedule C will not be included.
If you want Schedule C you'd have to complete some other lines there.
The attachment is the details of all your trades for the calendar year.
That means you'll have to file a paper return. [[This is so until Desktop TurboTax allows PDF attachments.]]
I have no idea how many MTM traders file with TurboTax and actually attach details, or make use of electronic media which IRS does not talk about.
Other tax software allows attachments for Form 4797.
