Can an employer deny its employees their vacation time or time off request for any reason, such as based on job performance?

An employer is under no obligation to provide any employee with compensated time off. The employer need not provide the same vacation benefits to every employee. The employer may condition receipt of vacation benefits on satisfactory attendance, performance, achievement or other terms. However, if vacation has been promised unconditionally in advance, the employer may generally not withhold vacation that has already been earned in accordance with the promise. Much depends on specific facts and circumstances you have not supplied. See an attorney.