The Social Protection Minister says he may remove disability payments from some of those in the Central Mental Hospital.
Normally when someone is imprisoned, welfare payments are stopped as the Prison Service exchanges information on a weekly basis.
However, those sent to the Central Mental Hospital are not convicted but detained after being found not guilty by reason of insanity.
Minister Leo Varadkar says he may be able to deduct the payments.
"One thing I have asked my department to examine is to whether we can deduct the cost of their accommodation and board from their welfare payments," he explained.
"There is precedent for that already. People who are in nursing homes, people who are in care homes make a contribution from their welfare payments to the cost of their accommodation, board and lodging," he added.