Unless you have farm income, there's no federal form that you'll need to file just to enter your ag exemption and Tax ID number.
If you have farm income, to
enter in TurboTax, enter "schedule f, profit or loss from
farming" in the search box, then click "Jump to schedule f, profit or
loss from farming."
That'll take
you to an interview, through which you can enter all your income and expenses.
