A senior official has left his job overseeing the new MPs' expenses system, saying he needs a break "for the sake of my health and sanity".
Nigel Gooding's departure as operations director of the Independent Parliamentary Standards Authority comes after reports of furious rows with MPs who claim the new system has left them as much as £20,000 out of pocket.
He confirmed that he left his post three months early, but denied he had been hounded out by MPs.
Mr Gooding told the Mail on Sunday: "I have left the job for the sake of my health and sanity. I was given the option of doing another three months with Ipsa but I felt I was just too drained to carry on.
"I have decided to take a break that I desperately need."
Some MPs are known to have protested in forthright terms over the way the new system - introduced after last year's expenses scandal - has been working. Ipsa agreed to give MPs £4,000 advances after some complained they were being forced to go into overdraft to pay for office equipment.
After Ipsa officials had borne the brunt of MPs' anger for the first few days of the new Parliament, a sign was put in the new MPs' reception centre asking them to respect staff.
Mr Gooding confirmed that the new expenses office was "a challenging working environment", but added: "I spent years as an amateur football referee. I have been called a lot worse on the football pitch than I was at Westminster.
"I am looking forward to relaxing for a few weeks and watching the World Cup."
Labour MP Paul Farrelly wrote to Mr Gooding two weeks ago, denouncing the operation of the expenses system as "prehistoric, amateurish, self-defeating and bureaucracy gone mad".
He told the Press Association last night: "The transition from the old system has been really poorly managed and administered. It has been consuming a lot of people's time. I came across one MP who seemed to be on the edge of a nervous breakdown because of all this."
Among Mr Farrelly's complaints were changes which meant staff pension contributions came out of MPs' office budgets, rather than being paid centrally by Commons authorities, which he said was adding 10% to the cost and forcing some members to lay off employees.
MPs were facing serious cash-flow problems because Ipsa requires them to buy basic office supplies, which were previously bought centrally, out of their own resources and then claim the money back.
In his email, he wrote: "I am already over my overdraft limit, have had to finance the replacement of the entire roof on my place in London and freeze ordering essential stationery supplies as I cannot pay for them and wait for Ipsa to reimburse me.
"As I have used my overdraft limit, my mortgage payment will bounce, causing me embarrassment and further charges. You could easily have saved us all this aggravation."
A spokesman for Ipsa said: "Nigel was an interim appointment and was appointed to oversee the operations from the planning through to the start-up phase, which he has done.
"Now he has made arrangements to move on."Reuse content