How to elect out of mark to market on my tax return?

Answer 1

That depends upon what you're talking about.

If it's a Section 1256 contract, you must Mark to Market. If you're a day trader with a separate investment portfolio you must elect Mark to Market by the filing deadline for the tax year PRIOR to the year in question.

There are other situations where Mark to Market come into play, such as PFICs so it depends upon what type of transaction(s) you are talking about.