NHS Highland overspent its budget by £3.4million between April and August this year.
Members of the health board will be warned that this could rise to £5million by the end of the year.
Finance director Nick Kenton will lay out a contingency plan when the board meet tomorrow in an attempt to cover the potential overspend.
But he will also warn that further contingencies will be needed to cover future risks.
Mr Kenton said: “There is a risk that a break-even on the revenue budget might not be achieved by year-end.
“The board has overspent by £3.4million on revenue for the first five months of the year. “There is a risk this trend may continue and in addition, there are high risks of £5.3million currently held outside of the forecast, with mitigation actions being worked through.
“A contingency plan roughly equating to £4.9million has been set out but this would leave very little leeway for covering any high risks that crystalise during the remainder of the financial year and my view is that a further contingency plan is required.”
The revenue budget covers regular expenditure, such as staff salaries, medication and surgical dressings.
NHS Highland’s capital budget, used for one-off projects, has been underspent over the same timescale by about £300,000.
The health authority’s financial problems has been in the spotlight after it required a £2.5million “brokerage” loan in 2013/14 from the Scottish Government which was needed to balance the budget.
Senior executives twice appeared before the Scottish Parliament’s public audit committee to answer questions about the debacle.
The need for a bailout was never discussed at the board’s public meetings and only emerged after the cash was approved.
The board is now paying the loan back at a rate of £500,000 a year.
During last month’s Scottish Government annual review of NHS Highland, chairman Garry Coutts said next year could be one of “stability and confidence”.