I would like to know which product to use for filing as "Mark to Market" Active stock day trader. I believe the forms to use would be IRS form 4797 and 6781?

[PattiF]

You can use either the Self-Employed in TurboTax Online or the Home & Business TurboTax Desktop for your activities as a "mark-to-market Active stock day trader.

[mccooney]

Where do I select the cost basis Mark to the Market for tax year 2021 on form 4797?

[AmyC]

When you file your first securities business return, you must elect an accounting period. On the Form 3115 filed for the year of change, a taxpayer should indicate that the taxpayer has filed the statement in compliance with section 5.03(1) of Rev. Proc. 99-17. See Form 3115 instructions page 4 right hand side for mark to market. You can file it with your return.

@mccooney