People looking after sick or disabled relatives provide care worth an estimated £23bn a year but receive benefits worth only £2bn a year, the Commons Public Accounts Committee (PAC) found.
There are an estimated 6 million unpaid carers, for whom the Government provides two main forms of support. The carer's allowance is paid to those who quit full-time work to provide care.
In addition, carers are given assistance to find employment that fits with their caring duties. But a PAC report says the benefits are "unnecessarily complex and cause confusion".
The labyrinthine system is difficult to understand and a fifth of carers find themselves defeated by the application process. The £2bn paid in benefits goes to 900,000 carers. But as there are 3 million sick or disabled people receiving disability allowances – whose carers could, in theory, qualify for financial support – this implies that up to 2 million may be missing out.