This is for Tableau: Create calculated fields to calculate the time$-$varying minimum annual

income to purchase a home under a $30-$year fixed$-$rate loan with a $20\%$

down payment and a $28\%$ debt$-$to$-$income ratio:

$Y_t=[\frac{1}{0\mathrm{.}28}*0\mathrm{.}8*Z_t*\frac{\frac{r_t}{12}(1+\frac{r_t}{12}{)}^n}{(1+\frac{r_t}{12}{)}^n-1}*12]+Z_t*x+$I,

for each date $t,$ where:

$Z_t$ denotes the Zillow home value at date $t($i$.$e$.,0\mathrm{.}8*Z_t$ denotes

the principal after a $20\%$ down payment$)$;

$r_t$ denotes the mortgage rate $($i$.$e$.,$ divide the "percentage" numbers

by $100)$ at date $t$

$n=360=12*30$ denotes the number of payment periods;

$x=0\mathrm{.}0108$ denotes the effective tax rate $($i$.$e$.,Z_t*x$ denotes

the property tax dollars paid annually$),$ and;

$I=1899\mathrm{.}0$ denotes the $($assumed$)$ time$-$fixed national average for

home insurance annual premiums