This is your marginal tax rate, the rate at which each additional dollar of income will be taxed. If you pay only Federal income taxes, it is the highest tax bracket you used when you calculated your taxes. Federal tax brackets currently are: 10%, 15%, 25%, 28%, 33%, and 35%. If you also pay state and/or local income taxes, these marginal rates can be added to the Federal rate. For example, if you had to pay 25% to the IRS and 5% to the state of Pennsylvania, your tax bracket is 30%. To perform a "pre-tax" analysis enter zero (0) as the tax rate.Mortgage Insurance is now tax deductible if your income is $100,000 or less for a couple, $50,000 or less for a single person.The period cannot exceed the shortest mortgage term. The period may be stated in fractions. For example, 25 years and 1 month would be entered as 25.083, 25 years and two months would be 25.167, and 25 years and 3 months would be 25.25, etc.This affects the after-tax analysis because on a purchase transaction points are fully deductible in the first year whereas on a refinance the deduction must be spread over the life of the loan.The rate of return changes with the length of time you stay with the mortgage, but not by very much.This classification by type of mortgage determines the mortgage insurance premium. If the mortgage is an ARM on which the initial interest rate holds for 5 years or longer (often referred to as 5/1, 7/1 or 10/1), select "Fixed Rate". If the mortgage is an ARM on which the initial rate holds for less than 5 years but it has rate adjustment caps of 1% or less, select "ARM w/Rate Caps <=1%.The premium rate is multiplied by the loan amopunt and divided by 12 to obtain the monthly premium. For example, a quote of 0.54 (percent) on a $200,000 loan results in a monthly premium of $90.If you enter a value, mortgage insurance will be terminated when the loan balance equals 80% of the appreciated value of the property.The premium rate is multiplied by the loan amount, and the product is added to the loan amount. For example, a quote of 1.5 (percent) on a $200,000 loan results in a new loan amount of $200,000 + $3,000 = $203,000.