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:
- That you're making an election under section 475(f);
- The first
tax year for which the election is effective; and
- The trade
or business for which you're making the election.
https://www.irs.gov/pub/irs-pdf/i3115.pdf
