<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/">
  <s:Body xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
    <CreateAccounts xmlns="http://tempuri.org/">
      <req>
        <Credentials>
          <UserName>yourusername</UserName>
          <Password>yourpassword</Password>
        </Credentials>
        <identify>youridentifier</identify>
        <Entities>
          <Account>
            <BrickId>00000000-0000-0000-0000-000000000000</BrickId>
            <OwnerAccountLabel>Test</OwnerAccountLabel>
            <Owner>9eefe173-8d54-4dc3-b8f7-5ac7bccdeec6</Owner>
            <AccountTypeKey>HoldingAccount</AccountTypeKey>
            <BaseCurrencyCode>SEK</BaseCurrencyCode>
            <AccountStatus xsi:nil="true" />
            <AllocationTemplate>00000000-0000-0000-0000-000000000000</AllocationTemplate>
            <ExternalReference>123456789</ExternalReference>
          </Account>
        </Entities>
      </req>
    </CreateAccounts>
  </s:Body>

//Create a new account with the CreateAccount method
var client = new BFSServiceReference.bfsapiSoapClient();

var credentials = new BFSServiceReference.Credentials()
{
    UserName = bfsusername, //Username of administrative user in your instance of BFS
    Password = bfspassword, //Password of the administrative user in your instance of BFS
};

var response = client.CreateAccounts(new BFSServiceReference.CreateAccountRequest()
{
    Credentials = credentials,

    identify = bfsidentifier, //Identifier is a unique token for your instance of BFS    

    Entities = new[]
    {
        new Account()
        {
			AccountTypeKey = "HoldingAccount",
            Owner = bnuserbrickid,
            OwnerAccountLabel = "Test",
            BaseCurrencyCode = "SEK",
            ExternalReference = "123456789",
            AccountStatus = 1,
            RequestReference = "My system reference",
            AcquisitionValueCalculationMethod = "Average",
			CustomFields=new CustomField[]
            {
                new CustomField
                {
                    FieldName = "TestField1",
                    Value = "Testvalue1"
                },
                new CustomField
                {
                    FieldName = "TestField2",
                    Value = "0.25"
                }
            }
        }
    }

});

foreach (var c in response.Entities)
{
    Console.WriteLine(c.AccountNo);
}