You elect the De Minimis Safe Harbor election so that assets that cost $2,500 or less can be taken as an expense this year and don’t have to be depreciated over time. To do this, an annual election must be made.
The questions about this election appear at the beginning of the Assets/Depreciation section for Schedule C (Business) or Schedule E (Rentals). (see the TurboTax FAQ below for more details, and click on "For 2017, items $2,500 or less")
If you didn't expense any purchases that would be included under this election, you may go back and change your answers. You can also keep the election as there isn't any harm in doing so.
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