Form Schedule C - Profit or Loss from Business is attached to your 1040 tax return (Line 12), for income earned while self-employed.
Other Expenses (Line 27a on your Schedule C) "Include all ordinary and necessary business expenses not deducted else where on Schedule C." For example: Amortization, Business start-up costs, etc. These expenses are listed in Section V, totaled on Line 48, and then that total is entered on Line 27a.
For more information - IRS Schedule C instructions: https://www.irs.gov/pub/irs-pdf/i1040sc.pdf
Form Schedule C:
https://www.irs.gov/pub/irs-pdf/f1040sc.pdf
