Write a summary of the following passage: Full-time employees earn vacation days at the rate of one day per month, or twelve days per year. Vacation time may be taken at any time, provided a vacation request has been submitted. The vacation request must be submitted to the supervisor as far in advance as possible and no later than a minimum of three business days before the desired vacation period begins. Failure to submit a vacation request within this time frame may result in the denial of the vacation time.