procedure ViewTaxInfoByCode(WebBrowser: TWebBrowser; Code: Integer);
var
  S: string;
  I: Integer;
  Headers: OleVariant;
  PostData: OleVariant;
begin
  S := 'B1=VIZUALIZARE&pagina=domenii&cod=' + IntToStr(Code);
  PostData := VarArrayCreate([0, Length(S) - 1], varByte);
  for I := 1 to Length(S) do
    PostData[I - 1] := Ord(S[I]);
  Headers := 'Content-Type: application/x-www-form-urlencoded' + #10#13;
  WebBrowser.Navigate('http://www.mfinante.ro/infocodfiscal.html', EmptyParam, EmptyParam, PostData, Headers);
end;

// possible usage
procedure TForm1.Button1Click(Sender: TObject);
begin
  ViewTaxInfoByCode(WebBrowser1, 1234);
end;