This will depend on the particulars of the barriers, but a good rule of thumb is disclose for a purpose; typically, this will be for the purpose of securing adjustments.
When you have identified a barrier which affects you on account of your impairment or some other similar situation where you will want your employer to make adjustments, then:
- Who: Find the person best placed to make the change. If your manager has asked you to write a report for a customer, talk to them and say "I can do that - but can you suggest someone who might be willing to check the spelling". If multiple people need to be involved, consider identifying a person who will help ensure cooperation (this will often be your manager) - discuss who is best placed to communicate what information to whom.
- When: Disclose in plenty of time for your employer to make arrangements, once you know it's likely to be a problem. If you need assistive technology from day 1, ask once you've agreed the offer. If you need level access at interview, ask for level access once you're invited to interview (or if there is a space for this on the application form, use this).
- What: Give your employer the specific information they need so they can focus on fixing any accessibility issues ("I have difficulty hearing in large meetings - can we please book the room with the hearing loop?"). If you're comfortable sharing more, do this only if you have reason to believe it would help and won't cause them to worry.
- How: Depends on your relationship with the other party; often you only have one or two appropriate methods. If it's once you're hired, look for opportunities to have a quick chat in a private room or out-of-the-way part of the workplace so the other party has the opportunity to ask clarifying questions, and follow up by email (hopefully thanking them for agreeing). In situations where you don't have a strong or trusting relationship with the person you're approaching, email is typically better.
In addition, keep track of who has been informed about these adjustments and consider checking that they're still understood and operational following personnel changes.
Disclosing excessive information, or to too many people, or unprompted at a time when you're not expecting anything to happen as a result is likely to invite unwelcome questions, discussion, or worry. Sadly, conscious and unconscious discrimination is still widespread (including among disabled people and in workplaces where disabled people are among the major 'customers').
Larger employers (in the UK at least) typically ask you during recruitment to fill in a questionnaire which an Occupational Health provider retains. If you are offered the job, they will look for any potential issues and discuss them. OH should then agree with you what information they will pass on to the employer. Any information they don't pass on, you don't need to share either. Not everywhere has this setup and in some places this setup the provider may take a negative outlook.
In any case, you should always answer questions honestly and factually, but if you feel uncomfortable, respond with your own questions to satisfy yourself that the information is being collected by the right person for a legitimate purpose. If this is a concern, find ways you're comfortable with for steering the conversation elsewhere, ideally by being reassuring. It's ok to say "I don't think that's relevant" or "That's not something you need to worry about".
In many jurisdictions, you will have a statutory right for the employer to make the workplace as accessible to you as they make it for everyone else wherever feasible, and statutory protections for making requests, (although this does not guarantee that your employer will respect the law, or that your case will succeed if they break it). In others you may need to ask specific questions as your treatment will be more variable.
Sometimes it may be beneficial to disclose for other purposes, for example:
- In the case of a visible (or otherwise obvious) impairment to clear misconceptions (some disabled people will mention fairly early on in a conversation with someone they've not met "By the way I'm not drunk, it's just...").
- If you have concerns that a job may involve work or working conditions that are genuinely not suitable for you and it is possible that there is no reasonable way for an employer to make sufficient adjustments, it may be advisable to check before accepting an offer. It is safest to do so once you have an offer.
It's a good idea to consistently take note of who you've disclosed information to, when, why, etc. This will help you if you find you're suddenly being treated differently.