We frequently hear employers mildly aggrieved when it emerges that an employee has a disability that they never declared on applying for a job.
In 2015, it was reported that 42% of disabled people seeking work found the biggest barrier to getting hired were misconceptions around what they could do. (Source ACAS)
The reality is that employees are not obliged to declare a disability either when applying for a job or during employment. If a job has particular demands you can make this clear during recruitment. But you cannot lawfully ask health questions prior to offering employment to an applicant. There are a few very specific exceptions. In some circumstances you may be able to ask about allergies, for example.
The Equality and Human Rights Commission warns: it is not possible for a job applicant to bring a claim against an employer just because they have been asked questions about health or disability which are not allowed. However, if an employer does ask questions that are not allowed and does not then offer the applicant a job, the employer could be liable for unlawful disability discrimination and, if so, will have to pay the financial damages that result from this.
It also follows that if you ask inappropriate questions prior to employment, and the employee conceals a disability, you have no comeback.
The answer is to make offers of employment that are subject to health checks and then to be careful that, if you withdraw the offer, you have sound reasons that you can justify. You will not be able to justify withdrawing an offer if reasonable adjustments could be made to enable the employee to perform.