It is entirely up to you whether to talk to your employer about your disability, and if so, at what stage you do this, who you choose to communicate with at work, and how you go about it. It is a good idea to keep a written record.
Remember, however, that if your employer doesn’t know about your disability, you will lose the benefit of any reasonable adjustments your employer would have had to make to your working conditions under the Equality Act 2010, as well as the other important protections the Act has to offer. It will also be much harder to access support services such as Access to Work.
Many specialist charities and not-for-profit organisations offer advice on how and when to talk to your employer about your disability.
You can choose to disclose information about your disability to your employer in such a way that the nature of your condition remains confidential to all except those who need to know. For example, all that your line manager needs to know is that reasonable adjustments are required, and not why they are needed.
You are not obliged to disclose information about your disability when you apply for a new job. Under the Equality Act 2010, with some narrow exceptions it is against the law for an employer to ask job applicants questions such as whether they have a disability and their previous sickness record before offering them a job.
There are some exceptions. For example, an employer can ask you whether you have a disability in order to make appropriate adjustments to the interview arrangements.
The ban on asking questions about sickness and disabilities extends to third parties such as recruitment agencies and assessment centres. The Equality and Human Rights Commission has prepared some guidance (PDF) on the ban.