The Ireland VAT Calculator irelandvatcalculator.ie is extremely handy and easy to use. I like that it supports all the Irish VAT rates — 23%, 13.5%, 9%, 4.8%, and 0% — and instantly shows both the VAT amount and the final price. The layout is clean, the calculations are accurate, and it’s great for quickly checking prices, whether you’re a business owner or just shopping. Definitely one of the more user-friendly VAT tools available. 

Hi,

In Odoo accounting, you can handle by this way..

1- Create the Advance Payment:

           - Create a new journal entry to record the advance payment received from the customer.

           - Debit the bank or cash account to reflect the increase in cash.

           - Credit a liability account (e.g., Deferred Income) to represent the advance payment received.

2 - Create the Invoice:

             - When you create an invoice for the customer, include the products or services being provided.

3 - Allocate the Advance Payment from the Deferred Income account:

             - Apply the advance payment received to the invoice to allocate the amount from the liability account.

              - In the invoice, add a new line and select the Deferred Income account and allocate the amount in minus.

              - Odoo will automatically create a journal entry for the invoice

Hope it helps