Rochdale Labour MP Simon Danczuk has agreed to repay more than £11,000 after a watchdog found he claimed extra accommodation expenses for two children who did not stay with him.
Independent Parliamentary Standards Authority (Ipsa) compliance officer Peter Davis said Mr Danczuk put in for the top-up cash over three years.
"The evidence points overwhelmingly to the conclusion that the MP obtained an increase to his accommodation expenditure budget by claiming dependant uplifts for his two oldest children for a period of over three years, when, at no point were either of the children routinely resident," Mr Davis's report said.
"The compliance officer must also conclude that this was done knowing that there was no reasonable prospect of the children staying at the accommodation."
Alongside the £11,583 excess, Mr Danczuk was also found to have wrongly claimed £96.50 in parking charges while on holiday in Spain.
In a statement, the MP said he had acted on what he "believed at the time" to be allowed and hoped Ipsa would review the rules.
"I am relieved that this issue has finally been cleared up and I will, of course, repay the full amount at the earliest opportunity," he said.