IRS Notice 2745C informs you that they do not have your correct address and they request it. They also usually include some correspondence regarding the issue.
Respond to Letter 2475C
Since it is important for you to receive IRS notices, you should complete Form 8822B and mail it to them by certified mail. When your next return is filed with your new address it will be changed but in the meantime you must continue to receive notices. It would be advisable to contact the IRS in several weeks to confirm that they received the address change form.
This notice often indicates that there is an underlying issue at stake or the IRS wouldn't need to contact you. It might be worthwhile to investigate your situation before a problem arises. Please complete the TaxHelpLaw Prep Steps prior to your consultation with Mr. Hopkins.