Thousands of people with caring responsibilities are missing out on credits they are eligible for which could boost their pension by hundreds of pounds a year.
Currently, only an estimated one in 20 (5%) of those eligible have signed up to receive these additional contributions which will fill gaps in their National Insurance records, the Government said.
Signing up for Carer's Credit for a year means a carer could receive more than £200 extra per year in state pension when they retire.
Pensions minister Baroness Altmann is calling on carers to check they are getting what they are entitled to and urging people to spread the word to carers they may know.
Only 11,000 people have signed up for the credit - but around 200,000 are thought to be eligible. The credit is designed for those who are caring for others for 20 hours or more per week and do not qualify for Carer's Allowance.
It helps carers to continue to build the amount of state pension they will receive, so they can protect their future pension while carrying out their caring responsibilities.
Signing up for the credit can particularly help older women. Women make up 130,000 - or 65% - of those who could be eligible, and two-thirds of those with caring responsibilities who could apply are estimated to be over 50 years old.
Baroness Altmann said: "It is important to recognise how much carers give to society, and I would like to see them receive what they're entitled to.
"If carers are not working full-time, these credits can fill gaps in their National Insurance record - helping to bolster the amount of state pension they will receive.
"It is straightforward to apply and doesn't cost anything. There is nothing to lose by signing up - and money to gain for the future. I'd like people to spread the word about this because I don't want to see anyone missing out."
People who think they may be eligible can get more information on how to apply by visiting www.gov.uk/carers-credit/overview.