IRS form 8822-B. It is now a requirement by the IRS that all Posts submit this form. This form must be submitted any time the post quartermaster changes and/or the post address changes. This is effective January 1, 2014. Source July/August 2014 VFW Checkpoint – page 2.
Here is the link to get the form and instructions – http://www.irs.gov/pub/irs-pdf/f8822b.pdf .
The way I read it – it will also apply to all Ladies and Mens Auxiliaries that have their own EIN number.