The municipality of Mostek planned to convert a former school into eight affordable rental apartments to attract new residents under the State Fund for Investment Support (SFPI) Affordable Rental Housing programme. We built a long-term financial model, assessed the town’s borrowing capacity against the fiscal-responsibility rule, and benchmarked subsidised SFPI financing against a commercial loan. The analysis confirmed the project was financially sustainable and showed that SFPI funding was markedly cheaper, giving the council the evidence it needed to proceed with confidence.