Nonresidents who sell their real property located in Maryland are subject to a nonresident withholding tax. That rate will increase from 6.75% to 7% for individuals for deeds presented for recording on or after June 1, 2012, and remains 8.25% for business entities. The withholding tax is based on the top state marginal income tax rate (which was increased in May) and the lowest income tax rate levied by local Maryland counties.
For more detail on nonresident withholding, click:
http://taxpros.marylandtaxes.com/guides/estatetax/requirement.asp