Do crises substantially change public support for taxes and spending, and why? We leverage the multifaceted character of the Covid-19 pandemic to test different theoretical micro-mechanisms usually confounded in observational research, or tested in isolation. Our randomized survey experiment provides four main findings. First, the economic and health dimensions of the crisis generated a substantial left-wing turn among the British public. Second, the effects are stronger on spending priorities (unemployment and health policies) than on who should pay for the welfare bill (progressivity of income and wealth taxes). Third, economic self-interested motivations are not relevant mechanisms to explain our findings. Fourth, framings associated with open borders and the global spread of the virus polarized welfare attitudes along immigration policy preferences. The generalizability of our findings, the prospects of redistributive conflicts after Covid, and the validity of established theories of welfare preferences in times of crisis are discussed.