You can specify the following for Greek Buyers:

Name: Their full name is specified in the PartyName/Name element.
Company ID: The buyer's TIN is specified in the CompanyID element. It must be valid and begin with EL
Tax Scheme: The buyer's Tax Scheme. This is always VAT.

Elements

Element	Description
`Invoice/AccountingCustomerParty/Party/PartyName/Name`	The buyer's full name.
`Invoice/AccountingSupplierParty/Party/PartyTaxScheme/CompanyID`
`Invoice/AccountingSupplierParty/Party/PartyTaxScheme/TaxScheme/ID`	Specify `VAT`.

Restrictions

The buyer's name must be there full name.
The Company ID must be a valid TIN and it must begin with EL.

Example

<ubl:Invoice>
   	<cac:AccountingCustomerParty>
		<cac:Party>
		<!-- Code omitted for clarity -->
			<cac:PartyName>
				<cbc:Name>CompanyFullName</cbc:Name>
			</cac:PartyName>
      <cac:PartyTaxScheme>
				<cbc:CompanyID>EL123456789</cbc:CompanyID>
				<cac:TaxScheme>
					<cbc:ID>VAT</cbc:ID>
			</cac:TaxScheme>
			</cac:PartyTaxScheme>
		<!-- Code omitted for clarity -->
		</cac:Party>
   	</cac:AccountingCustomerParty>
</ubl:Invoice>