How do you file an extension AND mark to market status online?

[Coleen3]

TurboTax does not support the Mark to Market election. 

The Mark-to-Market Election

A trader must make the mark-to-market election by the original due date (not including extensions) of the tax return for the year prior to the year for which the election becomes effective. You can make the election by attaching a statement either to your income tax return if filed without an extension or to a request for an extension of time to file your return. The statement should include the following information:

1. That you're making an election under section 475(f);
2. The first tax year for which the election is effective; and
3. The trade or business for which you're making the election.

https://www.irs.gov/pub/irs-pdf/i3115.pdf 

[tq2019]

How to attach a mark to market statement on Turbotax for online filing?

[VictoriaD75]

TurboTax does not support the MTM process. You can download the form from IRS. 

See additional information in the thread below:

Mark-to-Market Election