IRS Notice CP24 – Changes to Your Form 1040 The IRS sent CP24 to inform you of a discrepancy between estimated tax credits claimed on your return and credits the IRS posted to your tax account. This discrepancy resulted in a refund. Type of Notice: Return accuracy
https://www.hrblock.com/tax-center/irs/audits-and-tax-notices/irs-notice-cp24-changes-form-1040/