Hi there,
Thanks for reaching out to the Community. I'll be happy to answer your question regarding vacation in QuickBooks Online.
An employee's time off balance will automatically carry over into a new calendar year. For example, if an employee received 80 vacation hours per year with a maximum of 320 hours, the employee's vacation balance will continue to accrue until 320 available hours is reached, even if the period extends over several years.
There is no option to prevent carryover. If you have a "use it or lose it" policy (ex. unused sick time is eliminated at the end of the year), you need to change the employee's current balance at the beginning of each year.
For more info on this, check out this helpful article: Set up time off policy in Online Payroll. If you still have further questions, please contact our support team using this link.