Helen Miller, director of the IFS, has criticised the Chancellor's new Founders' Relief, writing on X that it "might be bonkers" and that she could not see an economic rationale for it.
"Sounds to me like it might be bonkers… Am struggling to imagine an economic rationale," Ms Miller wrote.
Paul Johnson, her predecessor as IFS director and now master of an Oxford college, agreed. "Funnily enough I was thinking the same thing," he replied on X.
IPPR was also sceptical of the relief, Scottish Financial News reports. The paper describes the think tank as closely linked to the Labour government.
John Healey announced the relief in his Budget statement today. It applies a 10% capital gains tax rate to lifetime gains of up to £10m. It is the first criticism of the measure from the IFS or IPPR.