According to the Marylant tax site, a non-resident of Maryland will need to file a nonresident income tax return to Maryland, using Forms 505 and 505NR, if he or she has income derived from TANGIBLE property, real or personal, permanently located in Maryland.

Suppose the ONLY income from Maryland souces of a nonresident of Maryland is some ordinary interest income (non-business) from his personal checking and savings accounts held in Maryland banks.

Is this ordinary (unrelated to business) interest income considered as "income derived from TANGIBLE property, real or personal, permanently located in Maryland"? In another word, dose the above-mentioned nonresident have to file a nonresident income tax return to Maryland?

If you have only the interest income, your income may be less than the filing requirement.

I would say that as a non-resident you do not need to report interest on a non-resident tax return. Reason is that "tangible property, real or personal" means physical assets that can be touched - real estate, automobiles, jewelry etc. "Intangible property" means financial assets such as stocks, bonds, promissary notes, and cash. Hence, you have no need to file in MD.

Here's an article that defines "tangible" for you: Tangible property - Wikipedia, the free encyclopedia