Do you have to accrue for paid time off if you are cash based?

The OP is asking if they have to book a liability for a time off accrual if they are using cash basis accounting.

Would need more information to answer but, it would be employment law that requires the PTO accrual if that is part of the organization's contractual employment obligation. And, it that case GAAP would require accrual basis accounting.

You might get by with cash basis for income tax purposes. But, using other than an accrual basis accounting system when you have material liabilities or assets would create a timing mismatch for revenues and expenses.