The widely underclaimed benefit tops up the income of people who aren’t entitled to the full state pension and also qualifies claimants for help with rent and council tax and the warm home discount.

Single pensioners can claim a weekly income of up to £182.60 while qualifying couples are entitled to £278.70.

In all, pension credit can be worth over £3,300 a year yet approximately one in three people entitled to receive it doesn’t currently claim it.

Sarah Pennells, consumer finance specialist at Royal London, said: “With energy bills due to rise sharply for millions of pensioners on 1 October, it’s more important than ever that people who have reached state pension age and think they may qualify, apply for pension credit.

“If you apply by 18 August and are successful, your application can be backdated, so you’ll receive the first cost of living payment worth £326, which the government has already started paying to existing claimants.”

Eligibility for pension credit can be checked on the Government’s Pension Credit calculator.

What benefits can you claim?

If you have a severe disability, you could get another £69.40 a week.

If you care for another adult, you could get an additional £38.85 a week, although pension credit as a carer is only awarded to those eligible for attendance allowance and carer’s allowance.

Pension credit entitles you to help with energy bills, rent and other costs, as well as a free TV licence if you’re 75 or over.

You can only receive pension credit once you reach State Pension age, currently 66, but you can apply for it up to four months before.

You can apply for pension credit online, by phone on 0800 99 1234 and by post. If you need help applying, contact Citizens Advice or Age UK.