Conguaglio: why December and leaver payslips change

Every payroll team that runs Italian employees meets the same question around the end of the year. Why did net pay change in December? The answer is the conguaglio.

What the conguaglio is  

Conguaglio means adjustment or true-up. In Italian payroll it is the recalculation of personal income tax (IRPEF) on the employee’s full-year income. The employer, acting as withholding agent, compares two figures:

• the tax withheld month by month during the year;
• the tax actually due on the total income for the period.

The difference is settled in the payslip. If too little was withheld, the employee pays the balance. If too much was withheld, the employee gets a refund through payroll.

Why monthly withholding is only an estimate  

IRPEF is an annual tax with progressive brackets. According to the secondary source we use, the brackets are:

• up to 28000 EUR a year: 23%;
• from 28000 to 50000 EUR: 33%;
• above 50000 EUR: 43%.

A monthly payslip cannot know exactly how the year will end. Each month, payroll applies the brackets to a projection of annual income based on what is known at that point. If the projection is right, the year closes with no surprise. In practice it is rarely exact.

Things that move the projection during the year:

• a raise or promotion;
• bonuses and one-off payments;
• variable pay such as commissions or overtime;
• unpaid leave or other gaps in pay;
• changes in the employee’s personal circumstances that affect deductions and tax credits.

Each of these makes the earlier monthly estimates a little wrong. The conguaglio is where the error is corrected.

Why December looks different  

December is the last payslip of the tax year. At that point all income for the year is known, so payroll runs the full annual calculation and compares it with the tax already withheld.

Three effects show up on the payslip:

• The December tax line no longer follows the monthly pattern. It carries the correction for the whole year.
• Net pay can go up or down. A bonus paid late in the year can push income into a higher bracket and raise the tax due. A year with lower income than projected can produce a refund.
• Gross pay may look normal while net pay does not. Teams that only reconcile gross figures will miss the cause.

For a platform, the practical point is simple. A December variance in net pay is not an error by default. It needs a tax explanation, not a payroll correction.

Why leaver payslips change  

The conguaglio does not wait for December when employment ends. When an employee leaves, the employer performs the recalculation on the income paid up to the exit date. The final payslip therefore carries the adjustment.

This catches people off guard. The leaver is not just receiving final pay. The last payslip also closes the tax position for the time spent with that employer. Final settlements, pay for untaken leave and other exit items increase income in the same period, and they are part of the calculation.

A leaver’s final net pay can therefore differ sharply from the previous month, even if the contract terms did not change. Employees often read this as a mistake. Support teams need a clear explanation ready.

What this means for EOR and payroll platforms  

A few points worth building into your process:

• Flag conguaglio lines. Mark the adjustment as its own item in the data you receive, so your system does not treat it as a normal monthly tax figure.
• Reconcile tax separately from gross. Compare gross to gross and tax to tax. A net variance alone tells you little.
• Warn employees early. A short note before December and before an exit prevents most support tickets.
• Model exits carefully. Forecasts for a leaver should include the recalculation, not just the last month’s pay.
• Keep the audit trail. Store the annual income used, the tax withheld to date and the balance settled.

The brackets above come from a secondary source. Treat them as an explanation of the mechanism, and confirm the current rates against official guidance before you use them in calculations.

The short version  

Monthly withholding is a projection. The conguaglio replaces the projection with the real annual figure. It happens in December and again whenever employment ends. If your systems expect a stable net pay in those two cases, they will raise false alarms.

Partnership teams that want to receive conguaglio data in a clean, structured form are invited to request the data-exchange specification.