Hello there, @ToriMC,
Let me share some insights about the payroll year-end key dates for 2018/2019 tax year so you'll be able to advance it to the next period.
It's possible the next financial year isn't yet open. This maybe the reason you're getting an error message after completing your year-end payroll.
Here are the key dates over the 2019/2020 year end period:
- End of the 2018/2019 tax year is April 5, 2019.
- Start of the 2019/2020 tax year is April 6, 2019.
Since you're unable to click the Advance to Next Period box, this option will be available by the end of the financial year. I'd suggest checking this button back on the last week of March since QBO is currently preparing all payroll forms for year end, such as P60 forms.
You can check out the set of articles if you're using QuickBooks Online Payroll (QBOP): Payroll Year End 2018/2019 for QBOP.
If you're using PaySuite, you can go through this helpful article: Payroll Year End 2018/9 in QuickBooks Online Payroll (PaySuite).
Don't hesitate to click the Reply button if you have other payroll concerns, I'll gladly help. Take care always!