Predicting the future tax burden will be difficult, but I recommend calculating your current cost of living (mortgage/rental costs, utility bills, taxes, travel costs, etc.) so you will have a baseline. When you move, your biggest expenses will be your monthly mortgage or rental payment and real estate and income taxes. You should be able to estimate those costs in the new area that you want to move to by looking at home values for the type of home that you want to move to. Real estate taxes are readily available at town assessor offices and the state income taxes are published as well. Since you already work in IL you are probably already paying IL income tax.