Lenihan I believe in 2011 during the financial crisis.
At the same time PRSI was added to all sorts of non-pay related income, non Pay Related "PRSI" that in almost all cases as far as I understand provides no entitlement to Social Insurance. Also tax relief on PRSI for pension contributions removed.
A major disadvantage of implementing a negative change against middle to high earners is that it's politically nearly impossible to reverse so we end up stuck with every dumb decision for decades or effectively life times.