Service Invoice Tax (ISS) Calculator for Your Clinic
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Issuing a service invoice is simple; knowing how much of it you keep is not. ISS depends on the municipality, Simples Nacional changes the math, and the client may withhold taxes. The calculator makes a simple estimate using the percentages you enter.
It does not replace your accountant. Your data stays in your browser and the starting values are a hypothetical example.
What does each field mean?
| Field | What to enter |
|---|---|
| Service invoice amount | The invoice total, in reais. |
| ISS rate | Your municipality's percentage for the activity. |
| Other withholdings by the client | Percentage withheld, if any. Leave zero if none. |
| ISS included in the Simples DAS? | Enter 1 if yes (separate ISS becomes zero) or 0 if no. |
How is it calculated?
- ISS = invoice amount × municipality rate (zero if included in the DAS).
- Withholdings = invoice amount × percentage withheld.
- Net = invoice amount minus ISS minus withholdings.
- Weight = (ISS + withholdings) ÷ invoice amount.
Worked hypothetical examples
Hypothetical example 1: a R$ 3,000.00 invoice, 3% ISS and no withholdings.
| Step | Calculation | Result |
|---|---|---|
| ISS | 3,000 × 3% | R$ 90.00 |
| Net | 3,000 minus 90 | R$ 2,910.00 |
| Weight | 90 ÷ 3,000 | 3.0% |
Hypothetical example 2: the same invoice with 5% withheld by the client.
| Step | Calculation | Result |
|---|---|---|
| ISS | 3,000 × 3% | R$ 90.00 |
| Withholdings | 3,000 × 5% | R$ 150.00 |
| Net | 3,000 minus 240 | R$ 2,760.00 |
| Weight | 240 ÷ 3,000 | 8.0% |
How do I use the result?
Use the net amount for pricing. If some patients ask for an invoice and others do not, the margins are different and the price can be adjusted, as long as it stays within the law and the contract. To compare tax regimes, see the Simples Nacional vs. individual tax simulator. And to see the impact on the month's result, the monthly net profit.
Frequently asked questions
What is the ISS rate for healthcare services?
The rate is set by each municipality, within the 2% to 5% range provided by Brazil's federal complementary law. Check with city hall or your accountant.
Do businesses under Simples Nacional pay ISS separately?
As a rule the ISS is already inside the DAS (the unified Simples Nacional tax payment). That is why the calculator lets you tick that option and zero out the separate ISS.
Can the client withhold taxes from my invoice?
Depending on the client, the activity and the municipality, there may be withholdings. Confirm with your accountant before counting on the full amount.