Normally 9.19% as your share (10.19% above €56,224 a year). The surcharges are usually not withheld on the tredicesima: leave them at 0 for the payslip net.
You have accrued 12 twelfths out of 12. The tredicesima is taxed at your 23% marginal IRPEF rate with no employment tax credits applied, so 30.08% of the gross is withheld in total.
| Gross tredicesima accrued | €2,000.00 |
| INPS contributions (9.19%) | −€183.80 |
| Taxable amount | €1,816.20 |
| IRPEF (23%, no tax credits) | −€417.73 |
| Estimated net tredicesima | €1,398.47 |
The IRPEF is worked out as the difference between the tax on the annual income with and without the tredicesima, so a bracket crossed halfway is not taxed entirely at one rate. The taxable income from the ordinary payslips used as the base is €21,794.40, which places the tredicesima in the 23% bracket.
The employee share is the pension (IVS) share of the Fondo Pensioni Lavoratori Dipendenti, Italy's main employee pension fund: 9.19%, with the employer carrying the other 23.81%. Above €56,224 of annual pay a further 1% applies, so enter 10.19 in that case. Apprentices and some sectors pay different rates, and the exact figure is on your payslip. The regional and municipal surcharges almost never appear on the tredicesima payslip, because they are settled against the annual total and withheld in instalments: leave them at 0 to see what actually arrives, or enter your combined rate to estimate the full-year cost.
Educational estimate, not tax or employment advice. Which pay elements count towards the tredicesima, and how an incomplete month is counted, are set by your CCNL (the sector collective agreement); the exact net also depends on the tax credits and surcharges applied on your payslip. Check with your payroll adviser or HR department.
Italian Thirteenth-Month Pay Calculator by Calculadora Capital