Is there an obligation to tell the employer about the disability?

No. It is up to any individual whether or not to tell their employer about their disability, but they should understand that if they do not, they may lose protection under the EA 10, as well as the chance to ask for reasonable adjustments (see page 172). Many specialist charities offer advice about the best way to manage disclosure of a medical condition, who best to disclose it to and on what basis. Workplace reps can also play an important role. A worker who has disclosed details of their condition should keep a careful record.