Which VAT codes do I use?

Use 'S' for standard rate, 'AE' for EU, and 'G' for export outside EU.

The main Peppol VAT categories are:

CodeMeaningUsage
SStandard rateWithin the same country
AEVAT Reverse ChargeSales to another EU country
GExport outside EUNo VAT
EVAT ExemptCertain sectors
OOutside scopeServices outside VAT

Use G for export outside the EU and O for services outside the VAT scope.