Though the total SDG financing gap is daunting, on the order of an average $400 billion per year for the world’s 59 low-income developing countries (LIDCs), it amounts to just 0.7 percent of the advanced economies’ GDP, and just 0.4 percent of the world economy as a whole. In this paper, SDG Costing and Financing for the LIDCs, SDSN proposes a plausible portfolio of financing actions that would increase budget revenues for SDG outlays by $430 billion—enough to close the SDG financing gap in all LIDCs and end extreme poverty.