Calculating Debt Payoff. If you have unpaid child support debt, you can figure out how long it will take to pay it off with our Arrears Payoff Calculator.Complete the fields below and press calculate to estimate alimony. The figures presented are based on legal California alimony guidelines. This California alimony calculator calculates California maintenance using the California county alimony formulas. The Payment Estimator applies the statewide uniform guideline calculation to the information that you enter into the blank fields. The California Maintenance Calculator uses the child support and related expenses entered into the calculator inputs to further reduce the spouses' net incomes. Our free California spousal support calculator helps you easily estimate your potential spousal support payments. Quick, easy, and accurate. Quick video on alimony.