Sales Tax Quick Card
The reverse direction is the one worth writing down. Divide, don't subtract.
BFCBrilliance · bfcbrilliance.com/tools/sales-tax-calculator
Both directions
- Add tax
- price x (1 + rate/100)
- REMOVE tax
- total ÷ (1 + rate/100)
- ⚠ NOT
- total x (1 − rate/100)
- Tax within a total
- total − (total ÷ (1 + rate/100))
- At 8%, the multiplier is
- 1.08 — multiply to add, divide to remove
- $108 at 8%, correctly
- $100.00
- $108 at 8%, the wrong way
- $99.36 — out by 64¢
- $1,200 at 20%, the gap is
- $40
- ⚠ Rates STACK
- state + county + city + district
- ⚠ Exemptions vary
- groceries, medicines, clothing — by state
Receipts to reconcile
| Date | Vendor | Total paid | Rate | Pre-tax | Tax |
|---|---|---|---|---|---|
Divide, don't subtract
The tax was worked out on the smaller pre-tax figure, so subtracting the same percentage from the larger total removes too much. Divide by 1 + the rate. On $108 at 8% that is the difference between $100.00 and $99.36 — and at 20% on $1,200 it is $40.
Look the rate up for the address
State, county, city and district rates stack, and two addresses in the same town can differ. Groceries, medicines and clothing are treated differently in many states. No calculator can guess this — which is why the rate is something you enter rather than something it knows.