The country's national constabulary is grappling with a cash crisis as it tries to balance the needs of day-to-day policing with with evolving criminal tactics, including a rising number of offences committed online.
Deputy chief officer David Page expressed the force's "disappointment" regarding the draft budget in a letter to MSPs, claiming the force's settlement continues a trend of "structural underfunding".
Writing to the Justice Sub-Committee on Policing, the top cop was critical of the spending plans announced by new finance secretary Kate Forbes on February 6.
Despite the force receiving an extra £17 million in its resource budget above what was expected before plans were announced, Mr Page said Police Scotland will still be dealing with a £49 million deficit in the next financial year.
In the letter, he said: "The draft funding settlement for policing in 2020-21 includes an uplift of revenue funding of £37 million, which is £17 million higher than originally anticipated.
"This is something that we welcome. It represents a 3.3% increase in the revenue budget."
But he added: "We are disappointed that the 2020-21 draft budget continues the long-term trend of Police Scotland being structurally underfunded."
Mr Page said Police Scotland made the Scottish Government aware of the need for £74 million in capital spending as far back as last summer but just £44.6 million has been proposed in the draft budget, £5 million of which is to be set aside to aid efforts to decarbonise the police fleet.
He wrote: "Whilst we are very grateful for the additional £5 million provided to support our ambition for greening the Police Scotland fleet, we are very disappointed that in real terms the capital available to Police Scotland (excluding the £5 million earmarked for the greening of the fleet) is actually a real-terms reduction on last year - which is the second consecutive year our available capital has reduced."
Mr Page added: "The impact of this settlement is that no new change improvement activity will be possible in 2020-21.
"This means, for example, that we will only be able to issue mobile devices to some of our officers, nor will we be able to commence the work to equip Police Scotland officers with body-worn video (BWV).
"This equipment, which is basic equipment issued to officers in England and Wales, was one of the key recommendations made by Dame Elish Angiolini's independent review into complaints handling, investigations and misconduct issues.
"This is a vital piece of equipment to assist in the safeguarding of officers health and safety and can be a key tool in the investigation of complaints against the police."
The capital budget is also used for maintenance of the police estate, which has been reported in recent months to be in need of repair in several places across Scotland - including a police station in Broughty Ferry where the roof collapsed last month.