When it comes to setting up VAT rates for Postponed Accounting and Relevant Contracts Tax (RCT), it is best to consult your tax agency to determine the rate you should use in QuickBooks Online (QBO). Since you are in Ireland, QBO automatically creates default tax rates for you. You can also create additional tax rates at any time.
If you need to change a tax rate, we recommend creating a new one rather than updating an existing one because the previous rate may have been used on previous transactions, and changing the rate may affect your sales tax tracking. Here's how to create a tax rate:
In the Tax Centre, select Add Tax.
Choose which type of tax rate you want to set up.
Enter the details of your tax rate. If you need help with this screen, select the help button (yellow question mark).