(a) The CMTR is a key element that greatly enhances the accuracy of the calculation of your RITA. Your agency uses the information on your “Statement of Income and Tax Filing Status,” as amended, to determine your CMTR, as follows (see subparts F and G of this part for information about the “Statement of Income and Tax Filing Status”).

(b) The CMTR is, in essence, a combination of your Federal, state, and local tax rates. However, the CMTR cannot be calculated by merely adding the Federal, state, and local marginal tax rates together because of the deductibility of state and local income taxes from income on your Federal income tax return. The formula prescribed below for calculating the CMTR, therefore, is designed to adjust the state and local tax rates to compensate for their deductibility from income for Federal tax purposes. Examples of how to calculate the CMTR are published in an FTR bulletin available at https://gsa.gov/ftrbulletins.

(c) The formula for calculating the CMTR is:

CMTR = F + (1 − F)S + (1 − F)L

(d) Your agency finds the Federal marginal tax rate by comparing your taxable income, as shown in your “Statement of Income and Filing Status,” to the Federal tax tables in the current year's Form 1040-ES instructions (see §§ 302-17.50 - 302-17.53 and §§ 302-17.63 - 302-17.65 for additional information on the “Statement of Income and Tax Filing Status”).

(e) Your agency finds the state and local marginal tax rates that apply to you (if any) by comparing your taxable income to the most current state and/or local tax tables provided by the states and localities. Every Federal payroll office and every provider of tax calculation software has these tables readily available, and the tables are also available on the Web sites of the various state and local taxing authorities.