At the request of the Spanish government, Spanish contributions to the CERN budget for 1964, 1965 and 1966 were reduced by 50%, 35% and 20% respectively. In a letter on 21 September 1966 to the Director-General the government asked for a further reduction of 35% from 1967 onwards. The CERN finance committee rejected the request.

Minutes of the CERN council, 19-20 June, 1969:

At the 40th Session of council last year, Spain asked that her notice of withdrawal from the organization contained in her letters of 8 August and 30 October should be held in suspense whilst her authorities studied further the possibility of her remaining in CERN.

By letter of 2 June 1969, Spain notified the Director-General that no solution had been found possible and that consequently her withdrawal from the organization would take effect as from 31 December 1968.

The council is now invited to take note of the withdrawal of Spain from the organization.

Spain formally withdrew from CERN on 31 December 1968.