An unprecedented overspend by hospitals and other NHS trusts is expected to be announced later by health bosses.
The figures for England from the regulator NHS Improvement cover the 2015-16 year, which finished in March.
By December - the three-quarter mark - hospital, ambulance and mental health trusts were already £2.2bn in the red.
That is predicted to have grown in the last three months of the year with experts warning the pressure it puts hospitals under has an impact on care.
The figures account for about two thirds of the entire £116bn health budget - they do not cover GPs, training budgets, public health budgets held by councils or any unspent money held by local health managers.
That means the Department of Health could still balance the books when the overall accounts are released later in the summer.
But the expected huge overspend still has the potential to impact on services