The Treasury committee has criticised several areas of the Chancellor's Right to Buy plans in a report on his latest Budget.
The intervention in the housing market may not even help first time buyers - the group the Government insists it is keen to support, MPs said.
They also said Mr Osborne's claim that increased demand will boost supply is "unconvincing".
MPs added that they "struggle to see the rationale for the taxpayer to stand behind loans for people wishing to own a second property".
The committee also warned the Government will come under "immense" pressure to extend Help to Buy in three years time, despite its status as "a scheme designed to deal with a supposedly temporary problem".