State tax filing

The simple answer is part-year resident.

Background...

What type of tax status you claim is often a matter of "domicile". Pennsylvania, like most states, defines domicile in this way:

You can have only one domicile at any given time. Your domicile does not change until you move to another state or country with the sincere intention of making your “new” permanent home there and abandoning your previous domicile.

If an individual moved to another state or country, but intended to stay there only for a fixed or limited time (no matter how long), the domicile does not change. Once established in a locality or state, your domicile continues there until you establish a new domicile. It is not dependent upon continuous physical presence. It is not abandoned by absence or even by presence in a former domicile, no matter how long continued, if, in leaving and during the absence, there is no firm, sincere, unconditional intention of remaining in the other jurisdiction for an indefinite and uncertain period. For example, temporary absence from a new domicile with presence in a former domicile for the purpose of transacting business or for the sake of health, pleasure, or education, with a definite intention of returning to the new domicile does not affect a person's domiciliary status.

In order to establish a new domicile, the following three conditions must be met-

1. There must be evidence of a firm and definite present intention to discontinue making the former domicile your primary base of operations;
2. There must be evidence of a firm and definite present intention to make the new domicile your primary base of operations; and
3. There must be evidence of actual physical presence and actual abode (transient, temporary, or permanent) in the new location.

If a person left their domicile to seek new employment intending to remain in the other location only if they find employment, there is no change in domicile. If all three requirements are met, the date of the change is the first day of actual physical presence in the new location.

Thus if this is a permanent move to Europe, you should take steps to show that this move is permanent, like buying property, entering a long-term lease, getting a residency visa for your new location, notifying the PA post office that you have moved (are you going to have your mail forwarded elsewhere in the US?), establishing new citizenship if applicable, and so on. There is no hard-and-fast definition of domicile, you just need to have documented evidence that this is a permanent move, if you are ever asked.

PA Instructions (page 6):

• (P) Part-Year Resident

 If you moved into Pennsylvania during 2024, fill in this oval even though you were a PA resident at the end of 2024. If you moved from Pennsylvania during 2024, fill in this oval even though you were not a PA resident at the end of 2024. PA law taxes part-year residents on all income from all sources while a PA resident, and all income (loss) earned, received, and realized from PA sources when not a resident of Pennsylvania. See the instructions on Page 43 for more information.

Note the italicized part - if after your move to Europe, you are still deriving income from PA sources, you may still be liable to file a PA part-year return.