Charging VAT or not depends on various things:
- Are you invoicing for goods or for services?
- Where is your customer based? UK, EU, outside the EU?
- Is your customer a business or a consumer?
The answers will dictate whether your sale is:
Standard rated (i.e. 20% VAT must be charged);
Zero rated (i.e. 0% VAT);
Exempt (also no VAT);
Outside the scope of VAT.
It is imperative that you get it right. Also, in some circumstances, it may be necessary to register for VAT in the country where your customer resides.
Most importantly – you must seek advice! And be aware that Brexit may change things.