Yes, include the Safe Harbor Election Form with your return. This allows you to expense capital assets that cost $2,500 or less. The questions about this election appear at the beginning of the Assets/Depreciation section for Schedule C (Business) or Schedule E (Rentals).
The election covers only the current tax year. If you didn't expense any purchases that would be included under this election, you may go back and change your answers. But there is no harm in taking the election when you don't use it.
Read more about this here: Safe Harbor Election