The Scottish Police Authority (SPA), the civilian oversight body for the new single police force, said ministers had "underestimated" the cost of integrating the computer systems of the old eight forces.
They have been given a £12 million integration budget for the next three years, almost the same as the information and com- munications technology (ICT) budget of an organisation one-tenth of Police Scotland's size, Holyrood's Justice Sub-Committee on Policing heard.
The SPA may have to sell off police buildings to make up the shortfall, its chairman Vic Emery told the committee.
Labour MSP Graeme Pearson said: "It seems to me the guy that comes and fits my washing machine has better IT support for his product delivery than we have for a police officer."
Mr Emery said: "I don't disagree with any of that.
"We need to work, and we are working, closely with the police so they can deliver their obligations to us, and so we can deliver them to you and the public."
Conservative MSP Margaret Mitchell asked if the £12m integration budget was "realistic or reasonably accurate".
SPA interim chief executive Andrea Quinn said: "I have previously said it was underestimated, and once the blueprint and strategy has been agreed I think it will show it has been underestimated.
"What should the number be? I don't know but that's what the strategy will tell us.
"In our professional view, when you look at an external company and its turnover and what it would invest in ICT it's a lot more than £12m over three years."
SPA chief information officer Martin Leven said the old Scottish Police Services Authority, which had an annual budget of around £105m, spent £3.5m a year on ICT.
Police Scotland, with an annual budget of £1.2 billion, has been given almost the same amount on average to integrate the ICT systems of eight forces.
He said: "We are talking, I would say, more than £12m over a three-year period to significantly invest in the IT infrastructure."
Mr Emery said: "We're not in the middle but we are part way down the journey of understanding where all our finances are and what we can do with them.
"For example, we have inherited a huge estate of property, and we don't need all of that estate.
"If we dispose of some of that estate we could use some of that money to put back into systems that will actually give us more benefits.
"But we can't answer those questions until we understand the end-to-end situation.
"It's fair to say that if you took it in isolation, £12m over three years won't give you the ICT systems you want, but there are avenues of making savings that could supplement that to make it much more viable."
Ms Mitchell laid out the litany of costly public-sector ICT failures over the years, including about £133m of cancellations and delays at the Crown Office, Disclosure Scotland and Registers of Scotland.
Mr Pearson, a former policeman, said: "I hope we will begin to see some flesh on the bones that will give an assurance, not to me because I'm lucky enough that I don't need to go out at 11pm to do streetwork any more, but to the 20,000-odd who are out there doing it for us."
Mr Leven offered some "comfort" to the committee by stressing they had already delivered large ICT projects, including a national management information system, on time ahead of Police Scotland's inception on April 1.