Useful, Usable, and Used? Buffer Usability During the Covid-19 Crisis

Macroprudential policies have been shown to be beneficial during booms but there is limited evidence on how well they operate during periods of stress. Using a difference‑in‑differences empirical strategy we test whether regulatory capital buffers, a key component of the Basel III reforms, helped to support lending provision by UK banks through Covid‑19. To identify credit supply effects, we exploit data on the universe of UK mortgages, which were outside the scope of government guaranteed lending schemes. We find that more constrained banks defended their capital surpluses to a greater extent during the pandemic, and did so by maintaining higher loan rates, lower loan values, and tighter terms on riskier lending. In contrast, banks receiving greater capital relief from the cut to the UK countercyclical capital buffer during the pandemic maintained more stable capital ratios, lending provision and risk‑taking capacity. Our results suggest regulatory buffers may be less usable than intended, but buffer releases can dampen these unintended consequences