Most states have laws that require employers to pay employees their wages with some minimum frequency—usually either twice a month (semi-monthly) or every other week (bi-weekly)—and some states require weekly or monthly payment of wages.
These laws are known as payday laws and also dictate when an employee who has been fired/terminated or quit must be paid their final paycheck—in some states, immediately; in some states within a certain number of days; and in some states on the next regularly-scheduled payday.
Payday laws vary from state to state and are usually included in a state’s statutes—often in the labor code or other statutes governing employer-employee relations.
In Missouri, the state's wage and hour laws require employers to pay their employees at least semi-monthly. Missouri Revised Statutes Section 290.080 mandates that all wages earned by an employee up to the fifteenth day of a month must be paid by the employer by the last day of the month, and wages earned from the sixteenth to the last day of the month must be paid by the fifteenth of the following month. Regarding the final paycheck for an employee who has been terminated or has quit, Missouri law requires that the final wages be paid no later than the next regular payday on which the wages would have been paid if the employment had continued. This means that the timing for the final paycheck can vary depending on the employer's regular pay schedule, but it should not exceed the time frame of the next regular payday.