this is the Federal Government's Internal Revenue Services (IRS) fax machine number for your taxes or your income tax return. If you need to fax a document to the IRS, this is the toll free 800 number the IRS has for tax payers in the united states. 
if you are wanting to know what is the fax number for the irs i give it to you ok
TeleTax: 1-800-829-4477 - Service that provides both recorded tax information and automated refund information
this is the faxing machine number i was able to find when i went to irs.com so if this is what you are looking for great. there you have it
Why you need the IRS Fax Number?
update, if this number is not working for you, you can visit the irs website at www.irs.gov they may have a new fax number it if was changed.