A man with a background in the military police was overpaid more than £24,000 in Pension Credit when he failed to declare two private pensions.
David Bone (66), who has children aged seven and 12, allowed his then partner to fill in the first form but then signed it.
He later completed a review form himself, again omitting to mention the private pensions, magistrates heard on Thursday.
Bone, of Pearl Court, Holbeach, was sentenced to 16 weeks in prison, suspended for 18 months, and ordered to pay £100 costs and an £80 victim surcharge.
He pleaded guilty to two counts of dishonestly making a false statement to the Department of Work and Pensions (DWP) with a view to making a gain for himself – the first offence was in October 2008 and the second in March 2010.
Paul Wood, prosecuting, said Bone was overpaid a total of £24,285.69 and the DWP is reclaiming the money from him.
He said the DWP investigated Bone after receiving information that he was being paid pension sums by Standard Life and Legal and General.
Solicitor Daven Naghen, mitigating, said Bone was living with his then partner when he made the first claim.
She was the one who filled out the form and he signed it.
Bone completed the next form himself, again omitting the pensions, but later brought it to the DWP’s attention that he was receiving the pensions.
Mr Naghen said: “He voluntarily brought it to an end.”
He said Bone was not receiving “huge sums of money” – he gets just under £700 a month from Standard Life and £108 from the other pension.
Mr Naghen said Bone was not living an extravagant lifestyle – he used the money he received to pay off the debts of his relationship when it went wrong.
Probation officer Chris Payne said Bone felt he was “slightly led astray in the commission of this offence but takes responsibility and must now live with the consequences”.
Bone had no previous convictions.