If you entered an asset in a previous year (2015 or earlier) that cost less than $2500, you can not change it now and take the election this year.

If you are entering an asset in 2016 that cost less than $2500 and you take the election, TurboTax takes you back to the main business page so you can enter it manually yourself in the Other Miscellaneous Expenses section. If you are filing a schedule C, find Other Common Business Expenses, then Other Miscellaneous Expenses.