IRS Tax Form 5213

Mail separate from a return. Not in TT.  https://turbotax.intuit.com/personal-taxes/online/deluxe.jsp#tax-forms

IRS form 5213 Election To Postpone Determination as To Whether the Presumption Applies That an Activity Is Engaged in for Profit contains a signature line and is filed separately from the Federal 1040 tax return.  Obtain the form from the IRS website.

File IRS form 5213 within 3 years after the due date of your return (determined without extensions) for the first tax year in which you engaged in the activity. 

If you elect a postponement and file this form on time, the IRS will generally postpone the determination until after the end of the 4th consecutive tax year (6th tax year for an activity that consists mainly of breeding, training, showing, or racing horses) after the tax year in which you first engaged in the activity. This period of 5 (or 7) tax years is called the “presumption period.” The election to postpone covers the entire presumption period.

However, 

• if you received a written notice that the IRS proposes to disallow deductions attributable to an activity not engaged in for profit (under Internal Revenue Code section 183), and 
• You want a postponement of the determination, 

you must file this form within 60 days after receiving the notice. This 60-day period does not extend the 3-year period referred to above.

If you elect a postponement and file this form on time, the IRS will generally postpone the determination until after the end of the 4th consecutive tax year (6th tax year for an activity that consists mainly of breeding, training, showing, or racing horses) after the tax year in which you first engaged in the activity. This period of 5 (or 7) tax years is called the “presumption period.” The election to postpone covers the entire presumption period.

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