Beside the standard income tax, “Taxes” should  include these unavoidable, and largely predictable outlays:

1. mtg installment… rent is a variable cost
2. compulsory school fees, excluding enrichment programs
3. medical insurance premium
4. telco charges
5. power + water + cooking gas
6. government taxes including pTax…
7. commute fares
8. car insurance … gas, parking, repair are variable costs
9. —– the other high-cost items are arguable avoidable —–
10. flights to see family members (at least once a year — predictable) but not unavoidable.
11. life insurance, critical illness insurance

These could add up to $3k – $5k a month. So my current after-tax income is more like $8k. Remember them when we say “this tuition only costs $150 a month”

Q: in my “staying alone” years, monthly total “tax” (excluding withholding) is …?
A: in US, it’s around $1k including rent and flights
A: in Singapore, it was probably below S$1k  including rent and flights. I used to rent 2 places.