Do you know when or if you need to file Form 3115 to Document "Accounting-Method Change"?

Form 3115 must be completed and filed if a trader files a tax return as a "trader in securities" without mark-to-market one year and elects the mark-to-market accounting treatment for the following year. This is a complicated form filed with the original tax return for the year of the change and a copy filed with the national office.