MINFin (Model for Informed National Financing) is an Excel-based, national-scale, cashflow model designed to facilitate discussions between Ministries of Energy and Ministries of Finance in low- and middle-income countries. The model supports power sector planning and financing by translating the technical demands of energy transition investment plans into financial strategies. It quantifies the financial requirements of these plans based on the specific composition and financing terms available to a country, comparing them to sector cashflows, helping determine their financial viability. MINFin also identifies potential financing gaps and explores strategies to address them, ensuring that energy transition plans are both technically feasible and financially supported.