rulebook, top of pg 42:
If a player is directed to lose anything (money,
checkmarks, etc.), but they cannot do so because they do not have a sufficient amount of that thing to lose,
they lose what they are able to lose and continue resolving the event. A character can never lose a checkmark
that would cause him or her to lose a perk, have negative money, or be brought below the minimum
experience required for his or her current level, and the town can never be brought below the minimum
prosperity for its current level.