"...a domestic LLC with at least two members is classified as a partnership for federal income tax purposes unless it files Form 8832 and affirmatively elects to be treated as a corporation." See this IRS webpage.
So you need to file a partnership return (unless you elected to be taxed as a SubS corporation). Then the LLC would issue K-1s to each of you to add to your returns.
The exception is if
- you and your girlfriend are considered married in your state, and
- you live in a community property state
In this case, you would each file a Schedule C on your 1040s, splitting the income and expenses in proportion to your involvement with the Airbnb.
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