Because of the passthrough structure of MLPs, unitholders in multistate MLPs may owe tax in each state in which the MLP earns income. The K-1 package provided to you by the MLP each year will include information on how much income has been allocated to you in each state.

Practically speaking, because of the large number of unitholders in any PTP and the deductions that are available to offset the income, the average investor is unlikely to have any significant tax liability in the states where he or she is a nonresident.   In fact, it is not uncommon to have a net loss.  However, because some states require filing even if no tax is owed, unitholders are advised to check the filing requirements of each state to be sure that they are in compliance.  Some useful links are below.