A man in his 80s who went years without claiming his state pension is due to receive a £140,000 payout.
He mistakenly thought he was not allowed to claim a state pension because he had continued to work long after reaching retirement age.
He is now set to receive more than a decade's worth of payments in one lump sum.
The error only came to light after Wakefield Council made inquiries on the man's behalf.
In a report, councillor Michael Graham said: "To help our residents get more money in their pocket, we are using information we hold to identify if they are entitled to more benefits and allowances than they are getting.
"One particular resident, an elderly gentleman in his 80s, who was in credit with his council tax but wasn't claiming the correct benefits.
"The gentleman is still working and didn't want to stop but didn't realise he could claim his state retirement pension and continue to work.
"We contacted the pension service, who looked into it and told the gentleman that he was due a backdated lump sum of £140,000 as well as an extra £185 a week."
The man has asked for his identity to be kept secret and declined a request to be interviewed, according to the Local Democracy Reporting Service.