Yes, you can write off the business expenses for your Amazon Affiliate income.  If your received a Form 1099-MISC that shows an amount in Box 7 for nonemployee compensation or a 1099-K and it’s because you did consulting work or other services for someone or a company, based on IRS regulation, you DO now "have a business!" You’re in the business of consulting and the IRS views you as a "company", and you have to file Schedule C to report that 1099-MISC income. The Schedule C is located in TurboTax Self-Employed version. This is a requirement, not an option!

The good thing about filing Schedule C is the ability to apply any expenses you incurred while performing those services.

Amazon Affiliates income is considered self-employment income and you have to complete a Schedule C which is found in TurboTax Home and Business (desktop) or TurboTax Self-Employed (online).

To enter this in TurboTax Self-Employed (online) or TurboTax Home & Business (desktop):

• Start under the Business tab
• How do you want to enter your business income?, then I'll choose what I work on
• In the "Business Income and Expenses" section, next to "Profit or Loss from Business", click Start or Update
• The next screen will ask "Did you have any income and expenses for a business in 2016?". Answer Yes.
• Follow the interview until you reach "Let's confirm your business info". Verify everything is accurate, then Continue
• Enter Business Information, click Continue (Your business name would be your personal name and your business address would be your mailing/personal address)
• Tell us about your business, click Continue
• Enter Employer ID Number, If Any, click Continue
• Do you use the cash method of accounting to run your business?, click Continue
• Did you make any payments that required you to issue a form 1099?, click Continue
• Do any of these uncommon situations apply to your business?, click Continue
• Let's confirm your business info, click Continue
• Your Business page
• Go to Business Income
• Business Income, then Click Start.
• General Income, click Start
• Tell us about additional income (Please note: it states Make sure to include any income reported on Form 1099-K and income from a barter or exchange)
• Type in your description,  click Continue

Hi TurboTaxPatrice, thanks for the helpful answer. Should you follow the same procedure if you have a negligible amount of income? For example, suppose I have $20 of Amazon Affiliate Income. How should I report it?

In this case, I obviously did not get a 1099-MISC or a 1099-K.