“Doing business” in a state is a legal term that refers to a business regularly carrying out its normal activities in a state that is different from its original registered jurisdiction, or having substantial contacts there. It’s also defined as having a presence in a state for legal and tax purposes. SPVs are considered businesses but they are fairly quiet and passive entities. The “doing business” question arises for SPVs when considering filing a Foreign LLC registration. Each state has a different “doing business” definition. Some states like California have broad sweeping wording and other states have more clearly defined provisions. See Foreign LLC.