Managers are expected to hand details of cutbacks in Lincolnshire's health service to the regional health authority on Monday.
The turnaround plan has been prepared by a special team, but its contents will not be released for several weeks.
A memo leaked to BBC News has suggested night-time emergency services could be reduced at Boston and Grantham.
The union Unison has warned there could be as many as 1,000 health jobs lost in Lincolnshire.
If accident and emergency departments at Boston and Grantham closed to patients after 2300 BST, Lincoln County Hospital would be the only centre providing these services in the area during the night.
Union officials have urged United Lincolnshire Hospitals NHS Trust to make the details public immediately rather than leave staff in the dark for several weeks.
NHS managers are also considering the suspension of fluoridation in the north and west of the county for a year to help reduce debts.
They need to reduce debts of £17.5m and stem the current overspend of almost £2.5m a month.