Possibly. Your dog walking app is likely going to be self-employment, yes, unless you can substantiate that it was a hobby. (If a hobby, you are limited in how many expenses you can claim, but you do not pay self-employment tax on that income). Here is an IRS website that discusses this topic: Five Basic Tax Tips about Hobbies | Internal Revenue Service
Airbnb, however, is different. If the income you receive was for less than 15 days of rental, then the income is excluded from your income. You don't count either the income or the expenses for tax purposes. And even if had more than 14 days of rental (15 or more), you might be able to claim the expense as rental income if you did not provide any personal services. Please see this TurboTax website with more information: How much tax on Airbnb income?
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