Private company established to enter into Agreements with the government to compensate the victims of negligent uninsured and untraced motorists. Every insurer underwriting compulsory motor insurance is obliged to become a member and contribute to the funding. The UK Guarantee Fund compensates victims of the motorists concerned when there is no other source of compensation. MIB also acts as the UK Green Card Bureau to ensure that the system operates satisfactorily in the UK. See UNINSURED DRIVERS AGREEMENT; UNTRACED DRIVERS AGREEMENT.