R/income_tax.R

In thmcmahon/taxFunctions: Income tax functions

#' Calculate income or superannuation tax liability. Defaults to 2012-13 tax
#' scales.
#' 
#' @param income Numeric. Gross income.
#' @param rates Numeric vector. Rate for each bracket.
#' @param brackets Numeric vector. Top of each tax bracket.
#' 
#' @export
#' 
#' @examples 
#' # Calculate tax liability for taxpayer with gross income of 50,000
#' income_tax(50000)
income_tax <- function(income, rates = c(0, .19, .325, .37, .45),
                       brackets = c(18200, 37000, 80000, 180000, Inf)) {
  income_by_bracket <- diff(c(0, pmin(income, brackets)))
  sum(income_by_bracket * rates)
}