The reversal interest rate is the rate at which accommodative monetary policy reverses and becomes contractionary for lending. Its determinants are (i) banks' fixed-income holdings, (ii) the strictness of capital constraints, (iii) the degree of pass-through to deposit rates, and (iv) the initial capitalization of banks. Quantitative easing increases the reversal interest rate and should only be employed after interest rate cuts are exhausted. Over time the reversal interest rate creeps up since asset revaluation fades out as fixed-income holdings mature while net interest income stays low. We calibrate a New Keynesian model that embeds our banking frictions.