If you rented your apartment less than 14 days, you don't need to
report anything. But Airbnb may issue you and the IRS a Form 1099-K to
report your rental income. So, you might get an IRS letter about the
rental income but you will need to prove that the amount is not taxable
because you did not exceed the 14-day limit.
For more information:https://turbotax.intuit.com/tax-tools/tax-tips/Rental-Property/Renting-Out-a-Room-on-Airbnb-or-FlipK...
However if you rented more than 15 days,
then you will need to report income and the expenses.In order to report these items, please see this link: https://ttlc.intuit.com/replies/3288530