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When academic degrees are mentioned in a generic way, often in combination with a field of study, lowercase both the degree and field and use the possessive form (except for the doctorate degree).

associate’s degree in communications

bachelor’s degree in chemistry

doctorate [or doctoral] degree in linguistics

master’s degree in creative writing

When academic degrees take the form of a spelled-out version of the official name of the degree (e.g., BA, MFA, BS, PhD, etc.), capitalize and don’t use the possessive form. However, lowercase the field unless it is a proper noun. 

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BA (Bachelor of Arts)

BS (Bachelor of Science)

JD (Juris Doctor)

MA (Master of Arts)

MArch (Master of Architecture)

MBA (Master of Business Administration)

MD (Doctor of Medicine)

MEng (Master of Engineering)

MPA (Master of Public Administration)

MPS (Master of Professional Studies)

MS (Master of Science)

PhD (Doctor of Philosophy)