Birmingham City Council will hand over £9m from its reserves to help with these 'operational' costs towards street cleaning and traffic management during the games.
But it is not yet clear where the remaining funding will come from at this stage.
Details emerged in papers going before the city council's cabinet next week.
The additional £15m comes on top of the £185.6m the council has already committed to help stage the games.
A report states: “In addition to the above costs, the council will also incur operational costs during the Games themselves (these may include additional costs associated with street cleaning, traffic management etc. as a result of the increased numbers of spectators at specific venues).
“Details of the extent of such additional costs will be fully developed in the lead-up to the games but are anticipated to be substantially funded through “business as usual” budgets in the first instance, with only genuine additionality that cannot be absorbed into day-to day costs being funded as a part of the Commonwealth Games programme.
“The full detail of these additional costs has not yet been confirmed, but an indicative estimate is that the total costs may be in the region of £15m."
In total the council will use £9.1m from council reserves - money held back for specific projects or emergencies - which were generated from underspends identified within the 2019/20 budget.
The areas where there are budget underspends has not been detailed.
City council leader Councillor Ian Ward, speaking ahead of the meeting, said: “We are a proud host city, so this funding will enable the council to get things in place so the city is ready to maximise the potential of hosting the games and the benefits the event will bring in the years beyond 2022,” he said.
“The need for these resources was always anticipated. Its use will not be directly related to the actual delivery of the Games. It will be used to improve the city for everyone who lives in, works in or visits Birmingham, with full details in the months ahead.
“Given we have funding available at this time, it is right to allocate it now because with more than two years to go until the Games, it gives the council as much time as possible to maximise the benefits from this increased investment.”
Work is already under way on creating the £73m Aquatics Centre, on Londonderry Playing Fields, in Smethwick.
Sandwell Council is contributing £27 million with £38.5 million coming from the Birmingham 2022 Commonwealth Games budget.
A further £7.6 million is funded by other external partners Sport England, Black Country LEP, Sandwell Leisure Trust (SLT) and University of Wolverhampton.