The HSE is overspending its budget by almost €1.6m every day.
Figures released this evening show an overspend of €432m in the first nine months of this year.
The HSE said that, based on current spending, it would overspend its budget by around €510m by the end of the year, but added it was in talks to try to reduce that amount.
Part of the overspend is down to a 42% increase in its spending on agency staff, which comes in spite of increasing numbers on the HSE's own payroll.
It also revealed a growing problem with waiting lists, saying the number of adults waiting eight months for an appointment had increased by 11% in just one month.