IRS Notice CP2501: Initial Underreporter Contact

Provide the requested information within the deadline (typically 30 days). Common responses: provide documentation showing disputed income was reported elsewhere, provide cost basis information for investment sales, or explain non-taxable reasons income appeared on an information return (such as a return of capital). A clear, documented response at CP2501 often prevents CP2000 altogether.

Ignoring CP2501 leads to CP2000 (formal proposed adjustment), then CP3219A (Notice of Deficiency), then assessment and collection. Responding at CP2501 is the easiest stage to resolve issues — documentation requests are simpler than disputing a formalized proposed adjustment.