The title that a person uses with their name can be a way of expressing gender. Some people don’t have a title or are against being referred to with a title.
Just like calling someone the correct name, using the right title for them - or not forcing them to use a title - is a sign of respect.
We’re talking here about common titles in English: Mr, Mrs, Ms, Miss, Mx. Mx is a title that does not imply a particular gender (in a similar way that Ms does not imply a particular marital status). Other titles can relate to someone’s academic, professional or religious role (like Prof, Dr or Rev), or be restricted to people who have certain roles in government or have received Royal Honours (like Rt Hon, or Sir). There can be rules around using formal titles.
However when using common titles, the right title to use for a person is the one they tell you to use. Common titles do not have a legal status, and there are no rules to say that a person needs to use a title that “matches” their name, gender or how they’ve been referred to in the past.
In most situations it’s not necessary to use titles. They can add an extra layer of formality, as well as adding the potential for awkward situations if you use the wrong title for someone. Consider not collecting or using titles.
If you do need to collect or use titles:
have an option not to select a title, if possible.
provide the gender-neutral Mx as an option alongside options like Ms, Mr, Mrs and Miss.
make sure you only ever use a title that was provided by the person - don’t guess someone’s title based on their name, pronouns or how you understand their gender.
provide easy options for people to change their own title without needing to explain (for example, self-service online forms).
don’t question or “correct” the title that people provide if you have other information about them, such as identification or a payment method that uses a different title.