World Health Organization developed the cMYP Costing and Financing tool to complement the WHO-UNICEF comprehensive Multi-Year Plan guidelines (cMYP). The tool is intended to support strategic planning for immunization program costing and financing and makes it easy to estimate past costs and financing for immunization, to aid in making future projections of resources requirements and financing, and for analyzing the corresponding financing gaps in reaching immunization program objectives. This user guide provides step-by-step instruction on how to use the cMYP Tool, guidance on sources of information, and results analysis, as well as guidance on interpretation of findings.