How much tax does a self-employed worker (partita IVA) really pay under the flat-rate scheme?

The calculation follows three steps, always in the same order. First: the year's receipts are multiplied by the profitability coefficient for your ATECO group. Second: from the resulting income you deduct the social security contributions actually paid during the year. Third: the 5% or 15% is applied to what remains.

The main coefficients:

• 40% - wholesale and retail trade, food industries, accommodation and catering
• 67% - trade activities and most services
• 78% - professional, scientific and technical activities, healthcare, education
• 86% - construction and real estate activities

A concrete example: a consultant receives €40,000 in 2026. The social security base is €40,000 × 78% = €31,200. The Separate INPS scheme at 26.07% costs €8,134. The taxable base drops to €31,200 − €8,134 = €23,066, on which the tax is €1,153 at 5% or €3,460 at 15%. Total tax and contributions: around €9,300 during the start-up period, around €11,600 at the standard rate - 23% and 29% of receipts. This is the total the calculator shows as its first result, before the breakdown. Watch out for a detail many calculators ignore: you deduct the contributions paid during the year, not those accrued. In the first year of activity, when you have not yet paid anything, tax is due on the full base - and that is exactly what the five-year projection makes visible.

Which social security scheme applies depends on your activity. Professionals without a category fund pay 26.07% of taxable income into the Separate INPS scheme (2026 rate): no minimums, you pay in proportion to what you earn.

Tradespeople and retailers work differently. There is a minimum income - around €18,800 in 2026 - on which contributions are due regardless: around €4,520 a year for tradespeople, around €4,610 for retailers, even if you have billed €10,000. Above the minimum, a further 24% (24.48% for retailers) applies to the excess. Anyone under the flat-rate scheme can ask INPS for the 35% reduction on all their contributions, both fixed and on the excess: the application is filed online and must be submitted by 28 February of the year in which you want it to apply. The flip side is that by paying less you build up less contribution seniority towards your pension. In the payment calendar the calculator also flags, for tradespeople and retailers, the four fixed instalments of the minimum contributions, alongside the balance and advance payments on the excess.

Anyone enrolled in a professional register with a category fund does not go through the Separate INPS scheme: they pay into their own fund (Forense, Inarcassa, ENPAP, CNPADC, ENPAM), with lower rates but minimum contributions to meet and, in most cases, the supplementary contribution billed to the client on the invoice.

For a professional, social security is not a free choice: it depends on the register. If your profession has a category fund - lawyers, engineers and architects, psychologists, chartered accountants, doctors and dentists - enrolment in that fund is mandatory and replaces the Separate INPS scheme. Anyone practising a profession without a professional order, or an activity with no dedicated fund, stays instead in the Separate INPS scheme at 26.07%.

The difference on the final bill is real. The funds apply main rates lower than the Separate INPS scheme (from ENPAP's 10% to ENPAM's Quota B at 19.5%), but they introduce two elements the Separate INPS scheme does not have: a minimum contribution due even on low income, and a supplementary contribution (2% or 4%) that you bill to the client on the invoice. The supplementary contribution is not a tax on you - the client pays it - but it changes the amount of your invoices and must be handled correctly. In the early years, with limited revenue, it is the minimum contribution that makes the difference: a fund with a minimum of around €3,180 (CNPADC) weighs more than one with a minimum of around €856 (ENPAP).

The calculator lets you select your scheme or fund and works out the total with the right parameters, so you immediately see how much social security weighs in your specific case. If you are also weighing a switch to the ordinary scheme, you can compare the two scenarios on the ordinary scheme page.

The profitability coefficient is a flat-rate deduction of costs: a professional at 78% is credited with 22% of expenses, whether they incur them or not. If your actual costs fall below that threshold, the flat-rate scheme almost always wins: the flat 15% beats IRPEF, which starts at 23% and reaches 43%, and on top of that you are out of VAT, withholding tax and sector studies.

The ordinary scheme comes back into play in three situations. When your actual costs clearly exceed the flat-rate figure - a retailer with thin margins can spend far more than the 60% credited by the 40% coefficient. When you have substantial deductions and allowances that you lose under the flat-rate scheme: mortgage interest, significant medical expenses, dependent family members, renovations. And when you make major investments with VAT to reclaim, which under the flat-rate scheme stays a dead cost.

There is no one-size-fits-all answer: it depends on receipts, costs, social security scheme and family situation. The quickest way to find out is to simulate both scenarios with your real numbers and compare the total taxes over five years.

Even under the flat-rate scheme, taxes are not paid in a single lump sum. The calculator reconstructs the calendar of deadlines from your result. By 30 June you pay the balance of the previous year's substitute tax together with the first advance payment for the current year; by 30 November you pay the second advance payment. The total advance equals 100% of the previous year's tax, split between the two instalments.

For those enrolled in the tradespeople and retailers schemes there are also the four fixed instalments of the contributions on minimum income, with quarterly deadlines, independent of the tax balance and advance payments. Seeing all the deadlines together helps you avoid being caught out: the five-year projection and the calendar are there precisely to help you mentally spread out the outlays, especially in the year of the switch from 5% to 15%, when the tax rises and the advance payments with it.