In Indonesia, personal income tax — known as PPh 21 — is withheld monthly by the employer on behalf of the employee. The withholding method and the December year-end reconciliation are the two most important concepts to understand.
Monthly Withholding — The TER Method
From January to November, monthly income tax is calculated using the Effective Tax Rate (TER) method. Under TER:
A flat effective rate is applied to the employee's gross monthly income.
The rate is determined by the employee's annual income bracket and their PTKP (non-taxable income threshold), based on marital and dependent status.
This provides a consistent, predictable monthly deduction.
December Reconciliation
In December, the tax calculation switches from TER to an annual reconciliation:
The full year's income is totalled and the actual progressive tax liability is calculated.
The amounts already withheld in January–November are subtracted.
Any remaining balance is collected in the December payroll — this can result in a noticeably higher tax deduction in December.
In case of a higher deduction in December, this is normal — it reflects the final annual reconciliation under Indonesian tax law, not an error.
Non-Recurring Income — Bonuses and Commissions
Bonuses, commissions, and other non-recurring payments are taxed separately in the month they are paid:
The non-recurring amount is annualised (multiplied by 12) to determine the applicable tax bracket.
If the annualised bonus pushes total income into a higher tax bracket, the marginal rate for that bracket applies to the excess.
This temporarily increases the effective tax deduction in the month the bonus is paid — it is not a permanent change.
To understand how non-recurring income is billed on payroll invoices, see What is non-recurring income (NRI) in payroll invoices, and how is it billed?