41 C.F.R. § 302-17.30

The purpose of the RITA is to reimburse employees for any taxes that they owe that were not adequately reimbursed by the WTA. As discussed in § 302-17.22, the WTA calculation is based on the income tax withholding rate applicable to supplemental wages. This may be higher or lower than an employee's actual tax rate. The RITA, on the other hand, is based on an employee's marginal tax rate, determined by their actual taxable income and filing status, which allows the agency to reimburse the employee for substantially all of their Federal income taxes. The RITA also reimburses employees for any additional State and local taxes that were incurred as a result of the relocation, because they are not reimbursed in the WTA process.