The company is eur based 1 of my customers is uk Based with uk currency Multicurrency enabled want to invoice uk customer in eur when i input invoice on gbp is allowed ?

It's nice to have you here, john139.

Base on the situation given, you'll want to set up a customer with a Euro currency and use this when creating an invoice.

To achieve this, you can follow the steps below:

1. Go to Sales.
2. Choose the Customers tab.
3. Click the New customer button.
4. Enter the customer's information, and click the Payment and Billing tab.
5. Choose EUR Euro from the This customer pays me with drop down menu.
6. Click Save.
   

Then, you can start creating invoice using the newly created customer.

Here's how:

1. Go to +New icon.
2. Choose Invoice.
3. Fill in the necessary information.
4. Click Save and close.

I'm adding this guide to become more familiar on how multi-currency works in QuickBooks Online (QBO).

Drop a comment below if you need more help or other questions. It's always my pleasure to assist. Have a great day ahead.

@john139 

Explore this payment service to deal with multi currency transaction. You may release invoice and get paid in Euro, and your customer will pay it in their local currency (e.g GBP for UK customers). It supports QBO.

https://veem.grsm.io/veems

Hope it helps.