Rate or rates in force determine which income tax rates apply for computation, deduction and advance tax obligations. The definition of 'Rate or Rates in force' specifies applicable income tax rates for an assessment or financial year: generally the rates in the Finance Act for the relevant year govern tax calculations, deductions and advance tax; for advance tax in specified categories the rates in those statutory provisions govern; for withholding obligations the Finance Act rates apply; and for certain cross border deductions the applicable rate may be the Finance Act rate or the rate in an applicable international agreement, whichever applies.