Do I add tax when invoicing foreign customers?

Hello, I'm a self-employed video editor with a handful of clients, and I'm a British citizen living in the UK. Some of my clients are based in the U.S. and one of them is based in Australia. I use Stripe to invoice my clients and it often asks me if I want to add tax to the invoices. My question is, do I need to tax U.S. and Australian clients on my invoicing system, if I am not registered for VAT (I don't currently meet the VAT threshold)? Thank you!

Hi Sam Ford,
Please have a look at the guidance here:
Exports, sending goods abroad and charging VAT
If you require further information, you will need to contact the VAT helpline here:
VAT: general enquiries
Thank you.