Yes, even if you don’t receive the appropriate forms, you’re still responsible for paying taxes on all of your taxable income. If you didn't make more than $5,000, PayPal doesn't send you a form. If you didn’t receive a 1099 form, you still need to report the amount of income on your tax return.
Refer to the TurboTax article What is Form 1099-K? for more information and instructions to enter your income.