By Ian Pollock
Personal finance reporter, BBC News
A deputy head teacher from Dorset has had her family's tax credits stopped - and been asked to repay a whopping £21,000 of the benefits, going back over the past four years.
Alexandra Roberts has a pile of tax credit paperwork
HM Revenue and Customs (HMRC) says the bulk of the money is owed because Alexandra Roberts, from Wimborne, did not tell them in the autumn of 2005 that she had separated from her husband Mark.
She says she did tell them, and can partly prove it as well.
However, the department will not allow her to backdate a new claim to the point when she split from her husband, alleging that her original claim was fraudulent.
Over the past six months, Alexandra has drained her savings to continue paying a full-time nanny to look after her two young children, while she continues to work as a deputy head teacher.
Now she has now sent them to live for a month with her retired parents in Spain, so that she can halt at least some of the outflow from her monthly salary.
"I am getting to the point almost of bankruptcy," she said.
Meanwhile, a Revenue official has pointed out to her that if she had told them of her separation on time, she would in fact have been entitled to more tax credits, not fewer.
Most of Alexandra's problems stem from the Revenue's belief that she did not tell them about her separation from her husband until November 2006, more than a year after the event.
One Revenue letter demanding nearly £10,000
But she says that a Revenue official, in a phone call, has already acknowledged that they might have been told earlier than that.
"When I phoned in June 2007, she said that a phone call had been logged on 27 October 2005, and that had set the ball in motion to look at my case again," said Alexandra.
"She said there would have to be something in that conversation to make them look at it again."
Meanwhile, Alexandra showed me two letters from the Revenue, addressed to both her and her husband, but at their now separate addresses, and dated 19 April 2006.
That appears to show that the Revenue did indeed know they had split up quite a while before November that year.
"They don't seem to know anything about my whole case," she says.
Legally, claims by a couple cease to be a claim when the couple splits up.
So the Revenue wants all the money back for the past two financial years - plus some more for overpayments in the previous two years - because it thinks Alexandra was trying to defraud it.
"She said, 'You've made a fraudulent claim, therefore we want all the money back'," says Alexandra.
However, fraud means stealing by lying.
In this case, it is hard to see how the Revenue has lost any money.
That is because Alexandra would probably have been entitled to more tax credits, not fewer, triggered by the removal of her husband's income from the calculations.
"She said, had I told them about the change, I would be entitled to more tax credits," says Alexandra.
But she appears to have fallen foul of a recent hardening of attitude at HMRC.
"The Revenue took a sympathetic view at one time," says Robin Williamson, a specialist in tax credits from the Chartered Institute of Taxation (CIOT).
"But concessionary treatment [when couples split up but fail to notify the change] was withdrawn a few months ago," he added.
Alexandra has already appealed against the Revenue's demand for the return of money, but it has decided it is right.
"There is no right of appeal against the recovery of an overpayment," a Revenue letter told her sternly.
Instead of looking after her children, Alexandra is now swamped by paperwork and is desperately trying to sort things out, helped by a local firm of accountants.
But they, too, have hit a brick wall with their efforts.
"She can take the dispute to the adjudicator or to the Ombudsman via her MP," said an HMRC spokeswoman.
To pursue her case further, Robin Williamson of the CIOT says she should contact the HMRC's own Data Protection Unit at Longbenton in Newcastle.
It should be able to assemble details of all her contacts with the HMRC, including correspondence, and give her recordings of her phone calls on a CD.
Williamson points to the example of a man who eventually got an alleged overpayment of £18,000 written off.
The man had moved to Portugal, but had mistakenly continued claiming tax credits.
The Revenue claimed it did not know of his move abroad and so asked for all the money back - even though it had, all along, been writing to him at his new address abroad.
"But it may be a long, slow, uphill struggle," warns Mr Williamson.