1. A computer system for determining an investment strategy for an entity with assets in a taxable account, assets in a tax-free account, and a mortgage, the system comprising interface components, a database, and an optimizer system, wherein the system is configured to: accept into the database information regarding: a total asset amount, an amount of assets in a tax free account, an amount of assets in a taxable account, a mortgage, a plurality of investments, an indicated percentage of the total assets to invest in each of the plurality of investments, and a time horizon; select, using the optimizer system, amounts to invest from the taxable and tax-free accounts randomly or using Genetic Algorithms (GA), such that the amounts substantially match the indicated percentage of total assets to invest in each of the plurality of investments; select, using the optimizer system, a value for a mortgage variable; and calculate, using the optimizer system, a return on investment for the entity based on the selected amounts to invest, the selected value for the mortgage variable, and the mortgage being paid out of the total asset amount; thereby determining an amount from the taxable and tax-free accounts to invest in each of the plurality of investments and a value for the mortgage variable that produce a maximal after-tax accumulation for said entity at the time horizon.