The answer depends on whether the benefits have been “vested” or not. “Vested” means that the vacation or fringe benefit cannot be taken away from you and must be paid out. “Unvested benefits” are not protected.
The employer can change its policy at any time to reduce or stop paying particular benefits in the future. As long as the company gives proper advance notice, then the policy can change and all further benefits cut off.
The company cannot take back any benefits that have already been earned or “vested” under the previous policy. But be careful about which benefits are considered “vested” so they are protected, and which are not vested and can be taken away.
For example, an employer has the option to quit giving vacation benefits. However, the company must allow the employees to use the vacation hours they’ve already earned.