"If their employer is not paying employers' National Insurance, unbeknownst to them they may not then be entitled to statutory maternitypay if they become pregnant, they may not be entitled to statutory sick pay if they fall ill, " he said.
Chancellor George Osborne has proposed a cap of 1% - which is below the expected rise in the cost of living - on increases in most working-age benefits, such as Jobseeker's Allowance and maternitypay, and tax credits for three years from 2013-14.