The tuberculosis targets for the UN Sustainable Development Goals (SDGs) call for a 90% reduction in tuberculosis deaths by 2030, compared with 2015, but meeting this target now seems highly improbable. To assess the economic impact of not meeting the target until 2045, we estimated full-income losses in 120 countries, including those due to excess deaths resulting from COVID-19-related disruptions to tuberculosis services, for the period 2020-50.Annual mortality risk changes at each age in each year from 2020 to 2050 were estimated for 120 countries. This risk change was then converted to full-income risk by calculating a population-level mortality risk change and multiplying it by the value of a statistical life-year in each country and year. As a comparator, we assumed that current rates of tuberculosis continue to decline through the period of analysis. We calculated the full-income losses, and mean life expectancy losses per person, at birth and at age 35 years, under scenarios in which the SDG targets are met in 2030 and in 2045. We defined the cost of inaction as the difference in full-income losses and tuberculosis mortality between these two scenarios.From 2020 to 2050, based on the current annual decrease in tuberculosis deaths of 2%, 31·8 million tuberculosis deaths (95% uncertainty interval 25·2 million-39·5 million) are estimated to occur, corresponding to an economic loss of US$17·5 trillion (14·9 trillion-20·4 trillion). If the SDG tuberculosis mortality target is met in 2030, 23·8 million tuberculosis deaths (18·9 million-29·5 million) and $13·1 trillion (11·2 trillion-15·3 trillion) in economic losses can be avoided. If the target is met in 2045, 18·1 million tuberculosis deaths (14·3 million-22·4 million) and $10·2 trillion (8·7 trillion-11·8 trillion) can be avoided. The cost of inaction of not meeting the SDG tuberculosis mortality target until 2045 (vs 2030) is, therefore, 5·7 million tuberculosis deaths (5·1 million-8·1 million) and $3·0 trillion (2·5 trillion-3·5 trillion) in economic losses. COVID-19-related disruptions add $290·3 billion (260·2 billion-570·1 billion) to this cost.Failure to achieve the SDG tuberculosis mortality target by 2030 will lead to profound economic and health losses. The effects of delay will be greatest in sub-Saharan Africa. Affected countries, donor nations, and the private sector should redouble efforts to finance tuberculosis programmes and research because the economic dividend of such strategies is likely to be substantial.None.