How this works
The calculation has two independent parts. Social Security is simple: 21.4% on 70% of what you invoice for services (or 21.4% on 20% if you sell goods or work in hospitality) — and zero in the first 12 months of activity. IRS is progressive: under the simplified regime a fixed fraction of what you invoice (the coefficient) counts as taxable income; the brackets run over that base. If you use the 0.75 or 0.35 coefficient, the part of the 15%-expenses you could not justify is added back (your SS contributions already count). Add IRS and SS, and you have your net.
Frequently asked
Why is Social Security ~15% of revenue, not 21.4%?
Because the 21.4% does not apply to everything you invoice. The base is the "relevant income", which for services is 70% of what you bill. So the real figure is 21.4% × 70% = 14.98% of revenue. People selling goods or in hospitality use a 20% base instead of 70%, so they pay far less.
I am in my first year. Do I really pay zero Social Security?
If you open activity for the first time you are exempt from contributions for the first 12 months from the start date. Since the regime only takes effect after those 12 months, no quarterly declaration is required in that period. From the 12th month the normal contributions and declarations begin. IRS still applies from day one.
What is the simplified-regime coefficient?
Under the simplified regime, the State ignores your real expenses: it assumes a fixed slice of what you bill is taxable profit. For listed professional services (art.151) it is 0.75 (75% counts as income); for other services 0.35; for selling goods, restaurants and hotels 0.15. Pick the one that matches your activity.
What are the expenses to justify on the 0.75 and 0.35 coefficients?
Anyone using the 0.75 or 0.35 coefficient must justify expenses equal to 15% of what they invoice. Social Security contributions already count toward that 15% automatically. If the rest is not backed by invoices (accountant, software, rent, etc.), the missing part is added to taxable income. This calculator adds that difference when you leave the expenses field low.
Does the estimate include personal deductions and the existence minimum?
No. It estimates gross IRS on your business income, before tax credits (health, education, invoice VAT, household) and the existence minimum. Those lower the final IRS. So the figure here is usually a ceiling — what you pay tends to be the same or less. For the exact value use the official simulator or an accountant.
DISCLAIMER
An honest estimate, not tax advice. It computes gross IRS on your business income (simplified regime) and the self-employed Social Security contribution, using 2025/2026 brackets and rates. It excludes tax credits (health, education, household), the existence minimum, withholding, VAT, the solidarity surcharge and other income — so it is generally a ceiling. IRS brackets depend on the year (pick it in the field). Always confirm with the official simulator and your accountant.