Senior officers have admitted a new single £60 million computer system is running nine months behind schedule. It will only be fully operational in September 2016 - three-and-a-half-years after the country's eight forces merged.
And a scathing report by HM Inspectorate of Constabulary in Scotland (HMICS) has highlighted serious concerns from front-line officers trying to work across eight computer systems that do not "talk" to each other.
In an inspection of traffic policing, HMICS found IT issues hampered "the effectiveness and efficiency of police reform and the ability of officers deployed in the new road policing structures to function fully at a regional or national level".
Inspectors stressed such problems affected national policing of all kinds - not just traffic matters - although it had less impact on operations confined to a single historic force area. Failure to integrate IT, they said, means officers in one former force area still cannot access basic information such as custody records or annual leave forms in another.
Police Scotland's solution to the problem is the so-called i6 system that contractor Accenture is adapting from the system used by Spain's Guardia Civil. This will be used for crime and accident reports and keeping track of evidence in court cases and lost property. But Police Scotland and its oversight body, the Scottish Police Authority (SPA), now only expect i6 to be operational by September 2016.
"The delay was unavoidable," said a report to the SPA from Deputy Chief Constable Neil Richardson. "However, no additional sums are payable … to the supplier, who [has] agreed to pay the additional technical costs necessary to meet Police Scotland's requirements."
Mr Richardson said the project design phase will be finished next month.
Graeme Pearson MSP, Labour's spokesman on justice and a former director of the Scottish Crime and Drug Enforcement Agency, said traffic police, whose job inevitably involves crossing old force borders, desperately needed effective IT support.
He said: "Year after year police officers are promised easy-to-use IT systems ... but here again is an official report that is scathing about that support. Millions in public funds have been thrown at IT and we still don't know what, if anything, we got for the money."
Niven Rennie of the Association of Scottish Police Superintendents, said Police Scotland "inherited a mess from legacy forces and is doing its best to fix this".
A Police Scotland spokeswoman said i6 would let officers deal with case and crime management from anywhere in Scotland by accessing a single system.
"The programme was extended following negotiations with Accenture, to ensure the delivery of Police Scotland's operational requirements for an integrated national system," she added.
An SPA spokeswoman said: "Past IT projects have encountered long-term problems because of a lack of focus in the early stages on agreeing the detailed design, and authority members have been assured that Police Scotland have a strong focus on this and are implementing the lessons learnt from previous projects."