The definition of 'penalty' ......
When the referee calls up a foul in the penalty area he awards a penalty. Nothing to do with an under occupancy assessment.
penalty
ˈpɛn(ə)lti/
noun
1.
a punishment imposed for breaking a law, rule, or contract.
"the charge carries a maximum penalty of ten years' imprisonment"
synonyms: punishment, sanction, punitive action, retribution, penance;
2.
(in sports and games) a handicap imposed on a player or team for infringement of rules.
"she only incurred 6.40 penalties for time on cross-country"
a kick or shot awarded to a team because of an infringement of the rules by an opponent.
"a penalty corner"
It is when the official name for Bedroom Tax is 'Spare Room Subsidy Penalty' as someone above quoted.