Good day, Martin. The VAT code you will use depends on what item you purchased and its location of sale.
The 0.00% Reverse Charge (RC) is for B2B transactions in the EU, specifically for mobile phones and computer chips. On the other hand, the 20.00% Standard reverse charge VAT for services (RC SG) applies specifically for goods and services from another EU country that fall under the standard VAT rate in the UK.
To ensure which rate to use, I recommend checking these references:
You can also reach out to your accountant for additional guidance on choosing the appropriate VAT code.
If you have any other concerns, please don't hesitate to reach out. We are here to assist you.