The macro budget for ambulance care is set down each year in the National Budget – to be precise in the budget of the Ministry of Health, Welfare and Sport (VWS) as part of curative care.
The Dutch Healthcare Authority (NZa) determines the budget that each Regional Ambulance Service (RAV) receives in order to make ambulances and staff available in its region. The NZa bases its determination of the regional budget required on capacity as calculated by the National Institute for Public Health and the Environment [Rijksinstituut voor Volksgezondheid en Milieu] (RIVM), on behalf of the Ministry of Health, Welfare and Sport, in the National Reference Framework for Distribution & Availability. The NZa does this based on policy rules, which are implemented by the health insurers. You can read in more detail about the budget system on the NZa website.