Must an employer agree to take part in early conciliation if contacted by Acas?

No, taking part in the early conciliation process is voluntary. Prospective claimants can bring a claim in the employment tribunal only if they have contacted Acas and have received an early conciliation certificate. However, neither the prospective claimant nor the employer is obliged to take part in conciliation. If either party decides not to take part, Acas will issue an early conciliation certificate without conciliation having taken place.