Many people have been overpaid tax credits
The tax credit system has been criticised for "completely unacceptable" errors, with one third of recipient families having been overpaid, according to a new report.
Many people in receipt of tax credit have told the BBC News website that they are still having problems - and are becoming increasingly frustrated and, in some cases, even desperate.
BBC News website offers some guidance.
I've been overpaid. What should I do?
If you have been overpaid, and expect your income for the current tax year to rise by more than Ј2,500, you must tell the HMRC.
But in the 2005 pre-Budget report it was announced that this threshold would rise to Ј25,000 in 2006.
You can either contact the tax credit helpline or write in to: HM Revenue & Customs Tax Credits, Comben
House, Farriers Way, Netherton, L69 1BY.
The tax credit helpline number is 0845 300 3900.
You must also tell HMRC about a number of other changes in circumstance.
More details are available in WTC2 - Child Tax Credit and Working Tax Credit - A Guide, available on the HMRC's website.
I'm worried about debt. Where can I turn?
If you are worried about debt, there are a number of free debt advice agencies which can help you.
Try Consumer Credit Counselling Service (0800 1381111), National Debtline (0808 8084000) or Citizens Advice (020 7833 2181).
I want compensation for extra costs. I have got a query which can't wait, and I can't get through to the helpline?
The government has told BBC News that it will not set up a separate compensation scheme for tax credits.