Almost £80m was spent on overtime to keep Northern Ireland's crisis-hit health service running over a three-year period.
Expenditure increased by more than 20% in that time, with staff working four million additional hours.
The annual overtime bill has risen from £23.5m in 2016/17 to £28m in 2018/19.
One health trust, the South Eastern, saw a 40% jump.
It is the latest revelation about the huge costs of addressing staff shortages in our health service.
Around £640,000 a day is also spent on agency staff to fill gaps in the workforce.
The annual bill is predicted to hit £230m this year.
In November this newspaper revealed one agency had been paid £1,600 to cover a single shift. In some cases, trusts have spent up to £155 an hour on agency workers.
The Belfast Telegraph reported how the Ambulance Service had spent £18m on overtime in three years to cover gaps.
Sinn Fein's Colm Gildernew, who sits on the Stormont health committee, said the rising costs of agency staff and latest revelations on overtime was symptomatic of a workforce crisis.
The MLA said the committee would raise the issue when it meets later this week. Officials from the Department of Health are due to brief members on a workforce strategy tomorrow.
The Department of Health's workforce bulletin shows there were 7,203 vacancies across the system as of October 2019. The latest bulletin is due to be published today.
Overtime costs, detailed in documents obtained by this newspaper, show:
Mr Gildernew said it was clear that the health service's workforce shortage needed to be urgently addressed.
"The Department of Health needs to bring forward a detailed workforce strategy that will begin to address vacancies in the Health and Social Care system in the immediate and medium term," he said.
"This needs to be considered in line with Minister (Robin) Swann's commitment to health unions to introduce a costed implementation plan for safe staffing levels within a short period.
"The high rate of agency staff spend is not a new development and along with wider workforce issues, will be raised by the health committee when it questions the Department of Health this week.
"Safe staffing levels and the reliance on overtime and agency staff is an issue that needs addressed urgently."
People Before Profit MLA Gerry Carroll, who also sits on the health committee, called for an end to the reliance on agency workers and staff overtime.
"This figure reflects a lot of what staff and their unions have been highlighting for years - that we have a serious issue with workforce planning across the health trusts," he said.
"We are faced with an overworked and underfunded health service and, instead of forking out huge sums of public money to agencies, staff should be properly recruited and employed by the health service.
"Now more than ever we must invest in and recruit staff that are paid a fair wage and not forced into working extra hours just to pay the bills."
The Belfast Telegraph reported last week that an international drive to recruit 622 nurses by March 2020 from overseas has achieved just half its target.
Some 420 new registered adult nurses have been recruited from EU and non-EU countries since the scheme began in January 2016. Of these, 374 remain in post.
Responding to an Assembly question, Mr Swann said he was confident the target will be met, adding: "Recent numbers have been increasing and current trends indicate that the target of 622 will be reached - and perhaps exceeded - within the coming months."
And last Thursday, British Medical Association Northern Ireland chairman Dr Tom Black told a Stormont co mmittee that an extra 1,000 consultants will be needed over the next 15 years.
The Department of Health did not respond to requests for comment.