A new report has called for more "honesty" in financial forecasting in the NHS.
Health trust chief executives and finance directors are frightened of publishing bad financial forecasts for fear of losing their jobs, claims the report by the Chartered Institute of Management Accountants (CIMA).
"Understandably, they may delay bad news for as long as possible, ignoring the worsening overspends to date and hoping for miracles," it says.
On the other hand, some may be deliberately pessimistic about budgets to help drive through savings, the report adds.
Accurate financial forecasting is crucial to ensuring health trust stay debt free but can be tactical or dogged by politics, says the institute, which examined the state of financial forecasting last year.
In-year Forecasting in the NHS draws on reports by the Audit Commission and other bodies to uncover common failings.
One of the key messages is: "The NHS financial regime, and the way that SHAs and DoH manage the NHS, don't always encourage accurate forecasting."
Steven Bliss, chair ofCIMA's NHS Group, said there was anecdotal evidence to suggest NHS finance professionals were under pressure to mask potential deficits and forecast what people wanted to hear.
But he added: "It is so hard to find firm evidence of that - it's always anecdotal."
However, former NHS finance director Noel Plumridge confirmed it had happened to him.
"There is a lot of pressure in forecasting during the year to present a forecast of break-even and it's quite common practice for any forecast that doesn't show break-even to be returned to an organisation with the question 'what are you going to do about it'," he said.
"Certainly in my experience I was told with one month to go to the end of the year that a forecast of a deficit was unacceptable and it would have to break-even."
Mr Plumridge feared the pressure was still on despite the DoH's efforts to improve financial forecasting practice.
"I suspect it's still happening now because even if the SHAs have relented, all trusts wish to be foundation trusts and break-even is a requirement," he explained.
CIMA's survey of more than 100 NHS finance professionals, most working in PCTs and acute trusts, found nearly a third quoted different figures to their board than to their SHA or Monitor.
More than a quarter reported their forecasts for income and spending in 2005/2006 were more than half a million out.
Meanwhile many forecasts were based on risky assumptions around spending.
"The report is about good practice - it's nothing people won't have thought about," said Mr Bliss.
"The worrying thing is good practice doesn't always happen."
However, he said there had been a recent culture shift aided by DoH measures that include ensuring trust boards and SHAs were given the same figures.
There was a new feeling that it was better to sign off "the truth", he said.
"Having a surplus doesn't seem as terrible this year - there's more of an acceptance that you don't always target to break-even," he added.