Form 843, Claim for Refund and Request for Abatement, is one of the principal tools taxpayers use to request a refund or abatement of certain penalties, additions to tax, interest, fees, or other amounts. But Form 843 is not just a form. The form itself is only the cover page. The substance of the request is usually the narrative: the factual chronology, legal basis, supporting documents, and explanation of why the IRS should remove or refund the amount at issue.