Deductions & credits

Wait a minute.  Did you get a W2 or a 1099Misc?  If you got a W2 you are an employee and don't fill out a schedule C for  business.  And that's a whole other problem.

If you meant you got a 1099Misc, then if you don't track inventory or cost of goods sold you can put materials under Supplies.

Go to Business tab- then Continue
Choose Jump to Full List -or  I'll choose what I work on

Then…..
Business Income and Expenses - Click the Start or Update button

Then click EDIT by your business name and the next screen should be a list of  topics,
Business Profile, Income, Inventory/Cost of Goods Sold, Expenses, Assets, and Final Details last.
 
Under Business Expenses, Click Start or Update by Other common business expenses
Supplies is about the 14th item down.

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