Technically, no. However, it is advised as an HR best practice. Simply put, you will avoid any false claims down the road, such as, “I was told I would be paid $24 an hour versus $18 an hour”. Putting the legal risks to the side, an offer letter starts the working relationship out on the
right track with transparency and clear communication. An offer letter does not need to be lengthy but should have several components: 

Job title, Pay amount; Pay type (exempt/ non-exempt); Pay schedule
(weekly; bi-weekly); Name of manager; Start date; At will employment (This is not a contract; you may quit or be terminated at any time); Your signature; Acceptance line for their signature. Attach any necessary documents such as a job description, a benefits package or guide, a non-disclosure
agreement and/or anon-compete policies (all requiring signatures).