IGF-OECD PROGRAM TO ADDRESS BEPS IN MINING TAX INCENTIVES IN MINING: MINIMISING RISKS TO REVENUE. SUPPLEMENTARY GUIDANCE: How to Use Financial Modelling to Estimate the Cost of Tax Incentives. Financial models are representations of the real world intended to give useful insight. They can be used to help governments make better-informed decisions, such as whether to provide a tax incentive to a mining project given the expected impact on government revenues and investor returns. Financial modelling is not new, although a lack of modelling expertise in developing countries compromises government efforts to design effective fiscal regimes and negotiate contracts. Outside of governments there are various organisations involved in financial modelling. The International Monetary Fund (IMF) uses the Fiscal Analysis of Resource Industries (FARI) framework to evaluate extractive industry fiscal regimes. In the future they intend to expand FARI modelling to assist revenue administrations to model the tax gap between actual and expected revenues. Practitioners in the non-profit sector include the Columbia Center on Sustainable Investment (CCSI), International Institute for Sustainable Development (IISD), Natural Resource Governance Institute (NRGI) and the Overseas Development Institute (ODI). OpenOil, a company based in Berlin, has developed an open-source approach to financial modelling of extractive industry projects and has published models of projects in Latin America, Africa and Asia. About this supplementary guidance – This guidance is focused specifically on how governments can use financial models to estimate the unintended revenue losses that result from mining investors changing their behaviour in response to tax incentives. It is intended to supplement Tax Incentives in Mining: Minimising risks to revenue, guidance material prepared under a programme of cooperation between the OECD and the Inter-Governmental Forum on Mining (IGF). It is not intended to replicate general guidance and technical assistance offered by international organisations, non-profits and private companies. Who is this guidance for? The guidance is for users who have some knowledge of financial modelling, such as government officials in ministries of mining or finance that are tasked with building financial models to advise decision-makers on fiscal regime design or contract negotiation. Knowledge of the basics of financial modelling is therefore assumed and this guidance does not teach users how to build a basic financial model of a mining project. The modelling tool adds new insights on how to integrate tax incentives into financial models and how to test the revenue impact of potential behavioural responses. See Annex 1 for suggested guidance material on basic financial modelling.