Abstract: The present invention provides a computer-implemented method of financial planning, budgeting and forecasting, using a computer-implemented Markov decision process-based model, wherein one or more e input parameters is associated with one or more uncertainty parameters that represent uncertainty in the associated input parameters and at least one of the input parameters is a desired output parameter. The input parameters are processed to generate one or more output parameters, and then the output parameters are re-input and the model re-processed until one or more of the uncertainty parameters is reduced below a pre-set threshold and one of the output parameters matches the desired output parameter. Once the pre-set threshold is reached, the output parameters are used to create a predictive financial plan, budget or forecast that accounts for uncertainty and is presented in a user-readable format.