How the B2B Calculator Works — Methodology Explained
Our B2B calculator converts your monthly invoice amount (gross revenue) into an estimated net take-home pay. Here's exactly how it does that — step by step with the underlying formulas.
Step 1: Monthly Revenue Input
Your starting point is gross revenue — the amount on your invoice to the client, excluding VAT.
If you bill hourly:
Monthly revenue = Hourly rate × Hours worked per month
The calculator defaults to 160 hours/month (standard full-time equivalent). You can adjust this.
Step 2: Social Security (ZUS) Deductions
Social ZUS contributions are subtracted from revenue. The amount depends on your business stage:
| Stage | Social contributions |
|---|---|
| Start relief (months 1–6) | 0 PLN |
| Small ZUS (months 7–30) | ~477 PLN/month |
| Full ZUS (month 31+) | ~1,507 PLN/month |
Note: On lump-sum tax, ZUS contributions don't reduce the tax base (tax is on gross revenue). On flat tax, they do reduce taxable income.
Step 3: Tax Calculation
Lump-sum 12%
Tax = Revenue × 0.12
Simple — no cost deduction. Flat 12% on gross revenue for qualifying IT services.
Flat income tax 19%
Taxable income = Revenue − ZUS social − Business costs
Tax = Taxable income × 0.19
Business costs (equipment, software, training, etc.) reduce the tax base.
Step 4: Health Insurance Contribution
Not a tax, but a mandatory cost calculated separately:
Lump-sum: Fixed amount by annual revenue tier:
- Up to 60,000 PLN/year → ~461 PLN/month
- 60,001–300,000 PLN/year → ~769 PLN/month
- Over 300,000 PLN/year → ~1,384 PLN/month
Flat tax: 4.9% × monthly income (minimum ~420 PLN/month)
Step 5: Net Take-Home
Net = Revenue − ZUS social − Tax − Health insurance − Business costs
This is your after-tax, after-ZUS monthly take-home — what you can transfer from your business account to personal spending.
Why Calculator Results May Differ from Reality
The calculator is a model. Your actual figures may differ due to:
- Tax reliefs: IP Box (5% for software copyright income), R&D deduction, child tax credit (on progressive scale)
- ZUS stage: The calculator uses full ZUS as default — select your actual stage
- VAT: The calculator works with net (ex-VAT) figures. If you're a VAT payer, VAT is a pass-through — not your income
- Individual costs: Enter your actual monthly business expenses for accurate results
- Small ZUS Plus: If your previous year's revenue was under 120,000 PLN, you may qualify for reduced contributions
How to Read Your Results
The calculator output is an estimate to help with:
- Negotiating your B2B rate vs. comparing employment offers
- Understanding which tax form benefits you most
- Planning monthly cash flow
For precise tax calculations, use certified accounting software or consult a licensed Polish accountant.
Try the calculator: B2B Calculator or B2B vs Employment Comparison.