As anyone with a master’s degree knows, attaining that level of education is a big achievement. People with master’s degrees can do anything from managing a business to teaching classes at a university. The correct way to address them depends entirely on the situation.
In Official Correspondence
When writing an official letter, begin with the recipient’s name and address in the upper left-hand corner of the paper. If you're addressing a colleague or someone above you in rank who possesses a master’s degree, write Mr., Mrs. or Ms. and their full name. If you're writing to your professor, use Professor and their full name.
In the salutation of the letter, use the same form of address you did in the heading. Write “Dear Professor” or Mr., Mrs. or Ms. and their full name followed by a colon. “Dear Professor” and the recipient’s full name also works.
Sometimes, people with master’s degrees choose to include them after their names on official correspondence. This is called a post nominal. In this case, write the person’s name as they've written it themselves, including the post nominal. For example, Mr. Felix Brown, MFA.
In Spoken Greetings
When speaking to a person with a master’s degree, you might not need to address them in an unusual way. For a colleague, you may refer to them by their first name or whatever they've told you to call them. For a superior, you might consider using a prefix, including Mr., Mrs. or Ms. followed by the person’s last name. When speaking to your professors at school, you can use “Professor” by itself, or you can use “Professor” followed by the person’s last name.
In Formal Introductions
If your school gives you the honor of introducing a speaker at an event, make sure you introduce them correctly. Use the speaker’s full name, often as it's written on their website or official publicity materials. In formal situations, refer to the speaker using Mr., Mrs. or Ms., followed by the person’s last name.
Personal Preference Is Key
If you don’t know how to refer to someone, ask them. Everyone has a specific way they want you to address them, and many people will tell you when they introduce themselves. If they don’t, find a way to politely ask them their preferred form of address. This comes up more often than you’d think. Many professors provide this information on their syllabi or on the first day of class.