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.
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Carers urged to claim credit to boost state pension
Pension experts at Mercer have identified the countries with the best pension systems. At number 10 is Singapore.
The system is based on the Central Provident Fund, which covers everyone in a job. Some of the cash can be withdrawn during your working life, and a prescribed minimum drawn down at retirement as an income.
Overall, Singapore scored 65.9 out of 100. It fared well on sustainability measures, and integrity, but relatively low incomes in retirement dragged its combined score down.
The UK scored 67.6 out of 100. The system was ruled to have great integrity, and good incomes in retirement. The overall scores were also up from the year earlier, as auto-enrolment was rolled out further, bringing more people into workplace schemes.
The researchers, however, were worried about how sustainable the system would be in the future. They called for an increase in minimum pensions, and added that more people ought to be encouraged into workplace schemes and persuaded to contribute more to their pension. They also wanted to see more people saving privately for their pension, and working later in life.
In Chile the state offers means-tested assistance, a mandatory centralised pension for employees to contribute to, and there are voluntary employer schemes.
Chile score 68.2 out of 100. Its highest score was for integrity, with another good mark for sustainability. Relatively low incomes in retirement let it down, and the researchers said the biggest improvements would come from raising the contribution levels.
Canada has a universal flat-rate pension - with a means-tested supplement. There’s an earnings-related pension based on lifetime earnings, plus voluntary workplace and private schemes.
It scored 69.1 out of 100. Its best score was for incomes in retirement, while it also performed well for integrity. Its only relative weak point was how sustainable it might be for the future - particularly because older people don't tend to stay in work.
Sweden has an earnings-related system with notional accounts - although this system was introduced in 1999 so it’s still in transition from a pay-as-you go system to a funded one. There’s also a means-tested top up.
Sweden was given 73.4 out of 100. It scored excellently for integrity, and well for sustainability. The overall score was brought down by incomes in retirement, and the researchers called for more workplace and private pensions.
Switzerland has an earnings-related public pension, a mandatory occupational system and voluntary private pensions.
It scored 73.9 out of 100. It fared well for integrity and reasonably well for incomes in retirement. The researchers just questioned its sustainability.
Finland has a means-tested basic state pension and a range of statutory earnings-related schemes. It scored 74.3 out of 100.
It had high integrity scores, with a less positive result for incomes in retirement, and a surprisingly low score for sustainability. The researchers called for higher minimum pensions, higher mandatory contributions and encouraging people to work longer to improve sustainability.
The Netherlands has a flat-rate public pension and quasi-mandatory earnings-related occupational schemes - which are industry-wide defined benefit schemes based on lifetime average earnings.
The system scored 79.2 out of 100. All its scores were high - particularly for the integrity of the system.
The system in Australia consists of a government scheme, a mandatory employer contribution into a pension, and additional voluntary contributions from individuals.
It benefits from the fact that all workers have been automatically enrolled in their company pension schemes for some time, so participation rates are high. The minimum contributions have also been raised recently, which means workers are building reasonable retirement incomes. It had an overall score of 79.9 out of 100, with the only question mark being over sustainability.
Denmark’s system includes a basic state pension, means-tested state top-ups, a fully funded defined contribution scheme and mandatory occupational schemes.
The researchers said it was "A first class and robust retirement income system". It scored 82.4 out of 100, with high marks across the board.