
Form 8697 Look-Back Interest: Who Files, How the Calculation Works, and What the New IRS Calculator Does
Form 8697 look-back interest settles the gap between estimated and actual results on long-term contracts reported under the percentage-of-completion method — the IRS recomputes prior-year income with final figures and charges or refunds interest only, without reopening those returns. This guide covers who must file under IRC Section 460, the three-step calculation, the separate-filing rule for interest refunds, and what the Excel PCM calculator the IRS released on May 29, 2026 does and doesn't do.










