Receiving an IRS CP504 Notice is serious. It is a Final Notice of Intent to Levy certain state tax refunds and a warning that the IRS may take additional collection actions if you do not respond....

If you’ve received an IRS CP503 Notice, it means the IRS is reminding you — for the second time — that your taxes remain unpaid. This notice is more urgent than CP14 or CP501 and signals that the IRS is moving close...

Receiving an IRS CP14 Notice means the IRS has officially assessed a tax and determined that you owe a balance. This is the first notice in the collection process, and it should not be ignored....