title: VAT validity check
body: <p>I have to build in some VAT formulas in a webpage.
  When a user fills in a VAT number, i have to check if it's in the right validity format.</p>
  
  <p>The control for Belgium is already done, but I can't find validity formulas for the Netherlands, France and Luxembourg...</p>
  
  <p>Anyone suggestions?</p>
  
  <p>I use Visual Studio .NET 2008, c#. Visual Basic is fine too :)</p>