Tredicesima Calculator

The tredicesima mensilita (literally "thirteenth monthly payment") is an additional month of salary that all employees in Italy are legally entitled to receive, typically paid in December ahead of the Christmas holidays. In English, it is often referred to as the 13th-month bonus salary or Christmas bonus, although it is not a bonus at all — it is a mandatory component of every Italian employment contract. If you are an expat working in Italy, understanding how your tredicesima is calculated is essential for accurate financial planning. Here is the step-by-step breakdown:

1. Gross tredicesima (tredicesima lorda) = RAL / 12. Your gross annual salary (RAL, or Retribuzione Annua Lorda) is divided by 12 to determine the gross amount of one additional monthly payment. If you have worked fewer than 12 months during the year, the amount is calculated on a pro-rata basis: RAL / 12 × months worked / 12.
2. INPS social security contributions: The standard employee-side INPS contribution rate of 9.19% is applied to the gross tredicesima. This deduction funds your pension (pensione), unemployment insurance, and other welfare benefits through Italy's national social security institute (Istituto Nazionale della Previdenza Sociale).
3. IRPEF income tax: The tredicesima is taxed at your marginal IRPEF rate (aliquota marginale) — that is, the rate of the highest tax bracket your total annual income falls into. Crucially, employment income deductions (detrazioni da lavoro dipendente) and the supplementary benefit (trattamento integrativo, formerly known as "bonus Renzi") do not apply to the tredicesima. This is the key reason the 13th-month pay feels more heavily taxed than a regular monthly paycheck.
4. Net tredicesima (tredicesima netta) = Gross tredicesima - INPS contributions - IRPEF. The result is the amount actually deposited into your bank account in December.

Because the tredicesima does not benefit from any tax deductions or credits, it is taxed more heavily than an ordinary monthly salary of the same gross amount. Many workers in Italy — both Italian and foreign — are surprised to find that their December bonus is 25-30% lower than their regular monthly net pay, even though the gross amounts are identical.

Month-by-month accrual: how the tredicesima builds up

The tredicesima does not appear out of thin air in December. It accrues progressively throughout the calendar year at a rate of 1/12 for each month of employment. In January you accrue 1/12, in February another twelfth, and so on until December when the full amount has accumulated and is paid out.

The fundamental rule for counting months worked is the 15-day threshold: a calendar month counts as a full month for tredicesima accrual if the employee worked more than 15 days in that month. For instance, if you start a new job on the 14th of a month, that month counts as a full month because you will have worked more than 15 days. Conversely, if you start on the 20th, only about 10-11 working days remain, so that month does not count toward your tredicesima accrual.

This 15-day rule applies symmetrically to both the start and the end of an employment relationship. In case of resignation (dimissioni) or dismissal (licenziamento), any tredicesima that has accrued but has not yet been paid is included in the final paycheck (ultima busta paga), calculated proportionally to the months worked during the year. For example, if you resign at the end of May having worked 5 full months, you will receive 5/12 of the full annual tredicesima.

It is important to know that the tredicesima continues to accrue during periods of paid leave, including annual holidays (ferie), paid personal leave (permessi retribuiti), public holidays (festivita), and sick leave within the protected period (malattia entro il periodo di comporto). However, it does not accrue during unpaid absences, unpaid leave of absence (aspettativa non retribuita), or zero-hours layoff (cassa integrazione a zero ore) — although in this last case, INPS pays a proportional amount on the worker's behalf.

Why the tredicesima is taxed more heavily than regular pay

One of the most confusing aspects of the Italian payroll system for expats is discovering that the tredicesima, despite having the same gross amount as a regular monthly salary, produces a significantly lower net payment. The reason lies in the IRPEF taxation mechanism applied to supplementary monthly payments (mensilita aggiuntive).

On your regular monthly salary, your employer (acting as a withholding agent, or sostituto d'imposta) applies employment income deductions (detrazioni da lavoro dipendente), which reduce the IRPEF owed. For 2026, these deductions can amount to up to 1,955 euros per year and are distributed across the 12 ordinary monthly paychecks. Additionally, for incomes up to 15,000 euros (or up to 28,000 euros under certain conditions), the trattamento integrativo (supplementary benefit, formerly "bonus Renzi") of 1,200 euros per year applies.

The tredicesima, however, benefits from none of these tax breaks. IRPEF is calculated by applying the marginal rate (aliquota marginale) directly — that is, the rate of the highest IRPEF bracket reached by the worker's total annual income. To illustrate: if your RAL is 30,000 euros, your income falls in the second IRPEF bracket (28,001 to 50,000 euros) with a marginal rate of 33%. This means that on your tredicesima, after subtracting INPS contributions, 33% of the remaining amount is withheld as IRPEF — with no deductions whatsoever to soften the blow. The result can be a net tredicesima that is 25-30% lower than your ordinary net monthly pay, even though the gross starting point is identical.

It is worth clarifying that this heavier taxation is not unfair or arbitrary. The employment income deductions have already been fully allocated across the 12 ordinary monthly paychecks, and the trattamento integrativo is paid out monthly. Applying them again on the tredicesima would effectively double their benefit, leading to a tax adjustment (conguaglio a debito) when you file your annual tax return (dichiarazione dei redditi) — in other words, you would owe money back to the tax authority.

Legal rights and obligations: what the law says

The right to the tredicesima mensilita for all private-sector employees in Italy is established by Presidential Decree (DPR) of 28 July 1960, No. 1070. This decree extended what was originally known as the "gratifica natalizia" (Christmas bonus) — previously only available in certain industries — to all subordinate workers. Before this law, the 13th-month pay was a contractual concession; after 1960, it became an irrevocable right guaranteed to every employee (lavoratore subordinato) in Italy.

For public-sector employees (dipendenti pubblici), the tredicesima is governed by Article 2 of Law No. 324 of 27 May 1959, and subsequent amendments. Pensioners also receive a tredicesima on their pension payments, as established by social security legislation.

Individual CCNL (Contratti Collettivi Nazionali di Lavoro — National Collective Bargaining Agreements) may provide terms more favorable than the statutory minimum. For example, the CCNL Commercio (Confcommercio, the commerce sector agreement) specifies that the tredicesima is calculated on the "retribuzione globale di fatto" (actual total compensation), which includes base pay (paga base), cost-of-living allowance (contingenza), seniority increments (scatti di anzianita), third-element pay (terzi elementi), and absorbable super-minimum payments (superminimi assorbibili). The CCNL Metalmeccanico (Federmeccanica, the metalworking sector agreement) contains similar provisions, with the additional clarification that sick leave within the protected period counts toward accrual. The CCNL Credito (banking sector agreement) mandates payment by 20 December each year.

Regarding payment timing, Italian law does not specify an exact date, but establishes that the tredicesima must be paid "in occasione delle festivita natalizie" (around the Christmas holidays). In practice, most employers pay it with the December paycheck, often in the first half of the month. If payment is late, the employee can file a complaint with the Ispettorato del Lavoro (Labor Inspectorate) or take legal action. Failure to pay the tredicesima constitutes a violation of the employer's compensation obligations and can result in administrative sanctions. The employee is also entitled to legal interest and inflation adjustment (rivalutazione monetaria) on the unpaid amount.

Special considerations for expats and foreign workers

If you are an expat who has recently moved to Italy for work, the tredicesima may seem unusual if you come from a country where "salary" simply means 12 equal monthly payments per year. In Italy, employment contracts almost universally specify either 13 or 14 pay periods (mensilita). When you negotiate your RAL during the hiring process, remember that a RAL of 30,000 euros paid over 13 months means your ordinary monthly gross is approximately 2,308 euros (not 2,500 euros), because one-thirteenth is reserved for the December tredicesima payment.

Workers benefiting from the impatriati tax regime (regime fiscale per i lavoratori impatriati) should note that the tax exemption applies to the tredicesima as well, since it is part of employment income. Under the current regime, qualifying workers may have up to 50% of their income exempt from taxation, which significantly reduces the IRPEF burden on the 13th-month salary. Use our Impatriati Tax Regime calculator to estimate the combined impact.

Finally, if you leave Italy mid-year to relocate to another country, you are entitled to a pro-rata tredicesima in your final paycheck, proportional to the months you worked during that calendar year. This applies regardless of whether you resigned or were terminated, and regardless of your nationality or contract type.

The table below shows the estimated net tredicesima for major RAL brackets in 2026, assuming 12 full months of employment and current IRPEF rates. These values are approximate and do not account for regional or municipal surcharges (addizionali regionali e comunali), which would further reduce the net amount by a small margin.