Yes, your employer can require that you use vacation time for any time off. All of my employers have had this policy. That’s the whole point of vacation time, to give you time off.

First off, you should realize that your company is not required by law to provide employees with vacation or other paid time off for personal use (including sick time). However, most employers recognize the value associated with providing these kinds of benefits in terms of attracting and retaining employees, and remaining competitive in the marketplace.

Second, since your company is using a PTO system differentiating between sick day or vacation day doesn’t matter. PTO IS flexible arrangement that gives the employee a set number of days off per year to be used at the employee’s discretion. These days can be used for sick time, personal days, vacations, or for whatever reason the employee may need time off. It may be useful to think of a PTO policy as a “bank” of hours from which an employee can draw, depending on his/her needs.

So PTO is treated like vacation time in California since you are entitled to payment for all accrued PTO days if you terminated your employment.

If you have a PTO program I don’t see why your employer is telling you how to differentiate when you take a day off. Although I would review your company’s PTO policies regarding taking time off; whether its vacation, personal, sick, etc..