You can call the
Treasury Offset Program Call Center at 1-800-304-3107 at any point
to learn more about the amount of your debt.
The IRS or the Department of Treasury's Financial Management
Service (FMS), which issues IRS tax
refunds, can offset or reduce your federal tax refund or withhold the entire
amount to satisfy the debt. Any portion of your refund remaining after an
offset will be refunded to you.
More info about refund offsets, including contact info and the appeals
process, is at IRS.gov (Tax Topic 203).