Why does the IRS want your state withholding?  IRS is only for federal.  Do you mean your state tax dept?

What does you state withholding have to do with the IRS?  The IRS only handles federal tax returns, not states.

Are you referring to state income taxes withheld from your wages and reported on a W-2?  If so, the state taxes withheld are entered on a federal tax return as an itemized deduction on Schedule A.  And entered on a state income tax return as a tax payment.

They say I have two checks one from 2017 and 2018 and I need to fax my state to them 

Yes state withholding I didn’t have correct address when they was sending check so I need my state to verify 

Please verify who you are communicating with, the IRS or your State?  How were you informed you needed to fax something to them?  By a phone call, email or did you receive something in the mail? 

What exactly are you trying to send?