Benefits cheats pretending to live alone are costing the taxpayer as much as £1.1bn a year, new figures show.

Couples who live together, whether they are married or not, have their joint income assessed to determine what benefits they are entitled to. 

But hundreds of “single swindlers” who lie about their living situation have cost the Department for Work and Pensions (DWP) an estimated £3.9bn in the last four years. Statisticians said the real number could be as high as £4.5bn in a worst-case scenario.

Investigators are using social media platforms such as Facebook, TikTok and Twitter to track down those lying about living with their partners. Others have been caught out by phone bills. 

Those found guilty face a maximum sentence of a decade behind bars.

Mother-of-six Emma Buck, 49, defrauded the taxpayer of £85,000 in benefits by saying that she was separated from her partner. But he had a key to their home and used the address on his own paperwork. She was spared jail after admitting the offences. 

Another case in 2021 saw Claire Finney, 42, who fraudulently claimed nearly £100,000, ordered to pay back just £11 a month. She had spent the money on five-star holidays in Cyprus. It would take her more than 700 years to repay the taxpayer in full. 

Another fraudster’s deception unravelled when her partner paid their internet bills. Becky Reed, 30, of Colburn, claimed she was a single mother between 2016 and 2021, and claimed £75,000. She was handed a 20-month suspended sentence in 2023. 

Estimates suggest that £7.4bn in benefits was fraudulently claimed in the last year, the equivalent of £20m every day. Another £2.4bn was paid out in error – meaning fraud and error accounted for £9.8bn of the £266bn benefits bill in 2023.

Other kinds of benefits fraud include working and claiming, failure to disclose assets, and landlord fraud, when a landlord knows a council tenant has moved out but continues to charge the authorities rent.  

The maximum prison sentence for a conspiracy to defraud is 10 years, according to the Sentencing Council. Other punishments include fines and permanent criminal records. 

Joanna Marchong, of the TaxPayers’ Alliance said: “Taxpayers will be left seething by these single swindlers.

“As the Government seeks to sort out the public finances, failing to ignore the billions that are being lost by this benefit fraud would be a breach of trust with Britons. The DWP should clamp down on this before these swindlers spiral out of control.”

It comes after Labour were rumoured to be considering axing the single-person council tax discount – a decision ministers have since ruled out.

Those who live alone are entitled to 25pc off their council tax bills, to reflect the fact that they benefit less from council services than families or couples. As of 2023, 8.4m Britons, including many older people, live alone. 

A DWP spokesman said: “This government will not tolerate fraud or waste anywhere in public services, including in the social security system. 

“We are determined to reduce fraud and error and are currently exploring all options on how best to achieve our goal.”