Operation Branchform was launched in 2021.
Police Scotland has spent more than £2 million on the investigation into the SNP’s finances.
The bill for Operation Branchform stood at £2,173,089 as of April 30, the force said in response to a freedom of information request.
The probe was launched in 2021 to investigate the SNP’s funding and finances and has involved several high-profile arrests.
Peter Murrell, the ex-husband of former first minister Nicola Sturgeon, has been charged with allegedly embezzling nearly £460,000 from the party.
The former SNP chief executive is set to appear in court on Monday.
Police Scotland said £100,498 has been spent on overtime in the five years since the investigation began. The force also said the £2 million figure does not include pension contributions.
The costs do not cover those accrued by the Crown Office.
Scottish Labour said the probe only adds to the financial pressures facing the country’s national police force.
Pauline McNeill, the party’s justice spokeswoman, said: “Given the dire state of the country’s finances as a result of SNP incompetence, the SNP must urgently clarify whether they intend to make any cuts to Police Scotland budgets in the years ahead.
“It cannot be the case that financial pressures are further heaped on the service as a result of the negligence of ministers, or because money has had to be spent investigating allegations of SNP fraud.
“Taxpayers should not have to foot the bill due to the actions of senior SNP figures, with our communities less safe due to any potential decline in officer numbers.
“The chief constable has already clearly stated the financial situation facing the force, with a significant shortfall in funding.
“The incoming Justice Secretary Neil Gray must heed this warning before it is too late.”
She urged Ivan McKee, who was this week appointed to the new role of Public Service Reform Secretary, to explain whether his job will require him to make “brutal cuts” to public services and whether this would include Police Scotland.
A spokesperson for the Scottish Government said: “We are providing record funding of over £1.7 billion for policing in 2026-27, a 5% increase compared to 2025-26.
“Scotland continues to have more officers per capita than England and Wales and the Chief Constable recently confirmed at the Criminal Justice Committee that the budget allocation will allow her to prioritise front-line services for our communities and to ensure that she can maintain officer numbers at 16,500 in the coming year. Allocation of resources is a matter for the Chief Constable.”
