An Garda Síochána overspent its budget by €32m in the first eight months of this year.
Commissioner Drew Harris told the Policing Authority that by the end of August, the force had spent over €1 billion and that cutbacks had been necessary.
These include a ban on garda overtime and deferred payments on IT and other projects.
The Commissioner's monthly report to the Policing Authority also says that almost 500 gardaí have been transferred from administrative to operational policing roles and that over 170 gardaí were off work after being injured on duty.
The overspend figure is an increase of €3m since the last monthly report.
Commissioner Harris says it has been necessary to identify "a range of capital and current expenditure adjustments to year end".
These cuts include a ban on administrative overtime and a reduction in operational overtime with the approval of the deputy commissioner now needed before An Garda Síochána can run costly anti-gang or terrorist operations.
Spending on some projects, such as IT upgrades and the development of the force's new Dublin Headquarters for the specialist units, has also been deferred but those payments will impact on next year’s budget.
An Garda Síochána has also to cover the estimated €15-€18m cost of the visits of US President Donald Trump and Vice President Mike Pence earlier this year.
A total of 495 superintendents, inspectors, sergeants and gardaí have been transferred from administrative positions to operational duties in the past two years.
The Commissioner also told the Authority that figures over the past five years show two observable crime trends - crimes against people such as sex crime and public order offences are increasing, while crimes affecting property such as burglary and criminal damage are decreasing.
He said the force closely monitors these trends on a regional and divisional basis and makes plans accordingly.
The report says the total number of garda members, staff and reserves is 17,735 of which 1,762 were on sick leave in August of this year. 173 of them had been injured in the line of duty.