The point being, it is still misleading in the extreme to say that Catholics generally and Carroll in particular were at that time proscribed from holding office. Carroll held an office when he signed the Declaration. Because of his efforts, and the efforts of many others, the Puritan phase was coming to a close and Maryland’s tradition of toleration was rapidly being re-awakened. Carroll went on to hold many offices in addition to the one he held as a signer of the Declaration.
Until November 1776, the law in Maryland barred Catholics from holding office. Carroll's service before this was during the time of transition.
From STARWISE's link above:
This change of sentiment found expression in Section XXXIII of the Bill of Rights of the Constitution of the new State of Maryland, adopted in November, 1776. In this article it is declared that all persons professing the Christian religion are equally entitled to protection. . .that no person ought to be compelled to frequent or maintain any particular place of worship or any particular ministry.