Average income tax by age 2015-15 vs 2003-04 (in 2015-16 dollars)

avgTax-vs-Age-1516-rel-0304

library(data.table)
library(grattan)
library(hutils)
library(magrittr)
library(ggplot2)

RQ("grattanCharts",
   devtools::install_github("hughparsonage/grattanCharts"))

library(grattanCharts)  # hughparsonage/grattanCharts

RQ("taxstats",
   install.packages("taxstats",
                    repos = "https://hughparsonage.github.io/tax-drat/",
                    type = "source"))
RQ("taxstats1516",
   install.packages("taxstats",
                    repos = "https://hughparsonage.github.io/tax-drat/",
                    type = "source"))
library(taxstats)       # hughparsonage/taxstats
library(taxstats1516)   # hughparsonage/taxstats1516

sample_file_1415 <- copy(taxstats::sample_file_1415_synth)
sample_file_1516 <- copy(taxstats1516::sample_file_1516_synth)


sample_file_1415[, fy.year := "2014-15"]
sample_file_1516[, fy.year := "2015-16"]

sfa <- 
  list(get_sample_files_all(),
       copy(sample_file_1415)[, fy.year := "2014-15"],
       sample_file_1516) %>%
  rbindlist(use.names = TRUE,
            fill = TRUE) %>%
  .[, WEIGHT := coalesce(WEIGHT, 50L)] %>%
  .[, WEIGHT := as.double(WEIGHT)] %>%
  .[, age_range := coalesce(age_range, Birth_year)] %>%
  .[age_range_decoder, on = "age_range"] %>%
  .[, Age.min := 70 - 5 * age_range] %>%
  mutate_ntile("Taxable_Income",
               n = 100L,
               weights = "WEIGHT",
               keyby = "fy.year",
               character.only = TRUE) %>%
  .[, CPI_rel_201819 := cpi_inflator(from_fy = fy.year, to_fy = "2017-18")] %>%
  
  .[, tax := income_tax(Taxable_Income, fy.year = .BY[[1L]], .dots.ATO = .SD), keyby = "fy.year"] %>%
  .[, taxNoAge := income_tax(Taxable_Income, fy.year = .BY[[1L]], .dots.ATO = .SD, age = 42), keyby = "fy.year"] %>%
  .[, real_tax := tax * CPI_rel_201819] %>%
  .[, real_taxNoAge := taxNoAge * CPI_rel_201819] %>%
  .[]

sfa %>%
  .[, .(avgTax = mean(real_tax)),
    keyby = c("fy.year", "Age.min")] %>%
  .[, change := avgTax - avgTax[fy.year == "2003-04"], keyby = "Age.min"] %>%
  .[, Year := fy2yr(fy.year)] %>%
  .[Year == 2016L] %>%
  .[, Age := Age.min + 2L] %>%  # cosmetic
  grplot(aes(x = Age, y = change)) +
  geom_bar(stat = "identity") + 
  scale_y_continuous(label = grattan_dollar) + 
  theme(legend.position = "right",
        legend.title = element_blank())