Selling on TikTok Shop is a business. What you pay for dropshipping is a business expense. You pay tax on your net business income, which is your total income minus expenses.
But the tag below your question says that you are using TurboTax Free Edition Online. You cannot deduct business expenses in Free Edition. To report your business income and expenses you have to upgrade to Premium Online, or use any version of the CD/Download TurboTax software.
