Many husbands and wives start business ventures together – it is a great thing to be able to work together to build something.
For state purposes, an LLC that has ownership interests issued to a husband and other ownership interests issued to a wife is considered a multi-member LLC for state purposes. Each person has his/her own set of ownership interests.
For federal income tax purposes, the classification of the LLC depends on whether the state of formation is a community property state (e.g., Arizona, Texas) or not.
The great majority of states are NOT community property states. In these states, a limited liability company owned by a husband and wife is considered a multi-member LLC and so is taxed, by default, as a partnership.
If the state is a community property state, then the IRS views an LLC owned by a husband and wife as a single member LLC and so it can be taxed as a disregarded entity. In other words, the LLC qualifies as a single member LLC for federal income tax purposes only.