Tanzania developed its 2016–26 health financing strategy to address existing inequities and inefficiencies in its health financing architecture. The strategy suggested the introduction of mandatory national health insurance, which requires long-term legal, interministerial and parliamentary procedures. In 2017/18, improved Community Health Fund (iCHF) was introduced to make short-term improvements in coverage and financial risk protection for the informal sector. Improvements involved purchaser–provider split, portability of services, uniformity in premium and risk pooling at the regional level. Using qualitative methods and drawing on the policy analysis triangle framework (context, content, actors and process) and criteria for procedural fairness, we examined the decision-making process around iCHF and the extent to which it met the criteria for a fair process. Data collection involved a document review and key informant interviews (n = 12). The iCHF reform was exempt from following the mandatory legislative procedures, including processes for involving the public, for policy reforms in Tanzania. The Ministry of Health, leading the process, formed a technical taskforce to review evidence, draw lessons from pilots and develop plans for implementing iCHF. The taskforce included representatives from ministries, civil society organizations and CHF implementing partners with experience in running iCHF pilots. However, beneficiaries and providers were not included in these processes. iCHF was largely informed by the evidence from pilots and literature, but the evidence to reduce administrative cost by changing the oversight role to the National Health Insurance Fund was not taken into account. Moreover, the iCHF process lacked transparency beyond its key stakeholders. The iCHF reform provided a partial solution to fragmentation in the health financing system in Tanzania by expanding the pool from the district to regional level. However, its decision-making process underscores the significance of giving greater consideration to procedural fairness in reforms guided by technical institutions, which can enhance responsiveness, legitimacy and implementation.