An NHS trust in Kent is asking employees to work extra hours for free as a way to ease its financial burden.
The trust wants to build a hospital and mental health unit at Pembury
A leaked letter from Maidstone and Tunbridge Wells NHS Trust said the idea was one of several to meet targets to secure a new hospital building.
The trust said it was an idea from staff after they were asked how to keep to budgets and work more efficiently.
The trust said the request was informal and completely voluntary and was to reduce its reliance on agency workers.
Plans are under way for the trust to build a multi-million pound hospital and mental health unit in Pembury under the Private Finance Initiative, but the letter hints at problems if targets are not met.
The memo, from director of human resources Terry Coode, said: "To be unsuccessful in our target will have serious consequences for the trust that will affect us all.
"It will jeopardise our investment and development plans, including our ability to build the PFI.
"To date we have avoided significant job loss as part of our financial recovery activity, unlike many trusts across the country."
As well as asking staff to work a day for free, the letter set out other ways job losses could be avoided.
These include voluntary redundancy, staff taking sabbaticals and carrying holiday days forward.
In a statement, Maidstone and Tunbridge Wells NHS Trust, said: "Our staff have suggested these ideas as part of wider plans to ensure we are working within our budgets.
"This informal request was extended to all staff, it is completely voluntary and we have had doctors offering to work extra hours for free.
"We think our staff do a great job anyway and if they want to help do a little more, that's entirely up to them and we thank them for it.
"If they don't that is fine too."