Ministers have tried to highlight the impact of benefit fraud by publishing some of the more unusual excuses used by people found guilty of cheating.
Reasons include carrying ladders as therapy rather than for cleaning windows, and claiming an identical twin had been doing work rather than them.
About £1.6bn is lost through benefit and tax credit fraud each year.
Some disability groups have warned the government against exaggerating the scale of the problem to justify cuts.
One excuse revealed by the Department for Work and Pensions (DWP) was: "I wasn't aware my wife was working because her hours of work coincided with the times I spent in the garden shed."
Another false claimant said: "We don't live together, he just comes each morning to fill up his flask."
In a case highlighted by the DWP, a man from Yorkshire claimed nearly £17,500 to look after his sick father - but had to admit to lying when his father revealed he had not seen his son for years.
In another instance, a man claimed more than £55,000 in disability benefits while he was working on a dairy farm.
Welfare Reform Minister Lord Freud said benefit fraud was serious, yet investigators were "routinely dealing with bare-faced cheek and ridiculous excuses for stealing money from the taxpayer".
"It's bad for the system because it drives it into disrepute. We want to spend the money on people who genuinely need it," he said.
"People stealing it for themselves means there is less money to go to where it is really needed to reduce poverty in this country."
Lord Freud said the introduction of Universal Credit would simplify and automate the benefits system, and make it much easier to catch people who made false claims.
But Richard Hawkes, chief executive of disability charity Scope, said: "The government really has to stop over-simplifying the debate on welfare and using unusual fraud cases to support changes which could have a serious and negative impact on the lives of hundreds of thousands of disabled people.
"We'd like to see the government put as much effort in to finding disabled people long-term sustainable employment."