The widely accepted definition for at-will employment is that the employer or the employee can end the working relationship at any time, with or without notice, for any reason or for no reason at all. Federal, state and local laws prohibit employers from firing an employee based on discriminatory factors, however.
With the exception of Montana, private sector employers in every state adhere to the at-will employment doctrine. The at-will employment doctrine simply means the employment relationship can be ended at any time, by either the employer or the employee, with or without notice, for any reason or for no reason. Upon reading the definition, many employees think it's just another law that favors employers; however, the at-will employment doctrine is actually very neutral given a complete understanding of the history of at-will employment and its lack of limitations.
Montana's exception is based on the practice that the at-will doctrine ends when the employee completes six months of employment. This gives employers the opportunity to cut their losses during a probationary period early in the relationship should there not be a good fit in terms of qualifications, performance or philosophy. Public sector employment is another exception to the at-will employment doctrine -- employees who work in the public sector, whether federal, state or some local governments -- cannot be terminated unless it's for good cause. Collective bargaining agreements and employment contracts are also exceptions to the doctrine. In other words, at-will employment applies to employees not otherwise covered by a contract.
Resignation and Notice
At-will employees are not required to give notice. According to the at-will employment doctrine, an employee can literally decide one moment to quit his job and walk out the door the next moment. Some companies refer to this type of resignation as job abandonment; however, even job abandonment is not a term defined by federal laws, although certain states use this term concerning claims for unemployment benefits. Many employees inform their employers via resignation letter or oral announcement that they intend to quit. An employee's intent to resign from his job doesn't have to comply with any kind of professional standard or courtesy such as the two-week notice period.
When an employee asserts her rights under the at-will employment doctrine, she could be subject to consequences related to the final paycheck and pay for accrued vacation. Under the Fair Labor Standards Act, there is no requirement for employers to give employees their final paycheck immediately upon resignation. That being said, if an employee who resigned doesn't receive a paycheck by the next scheduled payday, the U.S. Department of Labor, Wage and Hour Division provides assistance to employees who call for guidance. The employer's responsibility concerning final pay and compensation for accrued vacation is codified by state law -- not federal law.