Long-dated inflation swap contracts provide widely used estimates of expected inflation. We develop methods to estimate complementary tail probabilities for persistently very high or low inflation using inflation options prices. We show that three new adjustments to conventional methods are crucial: inflation, horizon, and risk. We find that: (a) U.S. deflation risk in 2011–2014 has been overstated, (b) ECB unconventional policies lowered deflation disaster probabilities, (c) inflation expectations deanchored in 2021–2022, (d) reanchored as policy tightened, (e) but the 2021–2024 disaster left scars, and (f) U.S. expectations are less sensitive to inflation realizations than in the eurozone.

This paper proposes a new method for measuring the impact of inflation on the real value of public debt. The distribution of debt debasement is based on two inputs: the distribution of privately held nominal debt by maturity, for which we provide new estimates, and the distribution of risk-adjusted inflation dynamics, for which we provide a novel copula estimator using options data. We find that inflation by itself is unlikely to lower the U.S. fiscal burden significantly because debt is concentrated at short maturities and perceived inflation shocks have little short-run persistence and are small.