How is tax revenue calculated?

Approximate Residential tax rates at 9% for low and mid density buildings per 2 squares (assuming 2x1 lots, that can grow to 4x3 lots)

       $    $$    $$$
low  4.0   6.5   3.75
mid  6.8  13.0  18.00

The steps taken in this experiment are:

  1. Prevent $$ and $$$ from appearing by setting their tax rates to 20.
  2. Create a $ residential area with 100% same density buildings with a known lot count, run cheetah until stable.
  3. Measure $ taxes.
  4. Let $$ in by lowering $$ tax to 9%, run cheetah until stable.
  5. Measure $ and $$ taxes.
  6. Let $$$ in by lowering $$$ tax to 9%, run cheetah until stable.
  7. Measure $, $$ and $$$ taxes.

Raw data:

low density testing with 20x22 = 440 2x1 lots

1800 total
$ 1800 = $4 * 440 2x1 buildings

2162 total
$  1142 = $4 * 285 2x1 buildings
$$ 1020 = $6.5 * 155 2x1 buildings

2142 total
$   658 = $4 * 164 2x1 buildings
$$ 1034 = $6.5 * 156 2x1 buildings
$$$ 450 = $22.5 * 20 3x4 buildings = $3.75 * 120 2x1 lots

mid density testing with 8*22 = 176 2x1 lots (2x3 buildings also occurred)

1214 total
$ 1214 = $6.8 * 176 2x1 lots

1342 total
$ 1045 = $6.8 * 153 2x1 lots
$$ 297 = $13 * 23 2x1 lots

1431 total
$  1013 = $6.8 * 149 2x1 lots
$$  195 = $13 * 15 2x1 lots
$$$ 223 = $18 * 12 2x1 lots

Based on this information, I can see what happened to my tiny map scenario mentioned in the question. I went from low density to medium density, and (in order to manage traffic), I de-zoned 40% of my residential zones.

1000 2x1 lots * $4 = $4000
 600 2x1 lots * $6.8 = $4080

Which explains why my population doubled but my residential taxes did not increase.


Some more data of my own here:

I have 1956 poor sims living in 184 poor low density 2 square houses. I get 824 in taxes from poor residents. Tax rate for poor sims is 9%

tax/sim = 0.42126
tax/poor low density 2 square house = 4.478

David B's data said 4 tax per poor low density 2 square house where as mine said 4.478. I counted carefully.

I am playing on easy setting though so that may explain why I get more tax.