If you agree with the proposed changes in the notice, you can follow the instructions and accept the changes quickly.

If, however, you disagree with the proposed changes, the process takes longer. From the time you respond to the notice, you can expect a turnaround time of approximately 8 to 12 weeks, per the IRS. If the IRS has a backlog, it will send you a letter indicating the additional time that it will take to respond (typically an additional 30 to 60 days).