The Luxembourg tax year is the calendar year.
The total income of a husband and wife and the non-salary income of minor children forming part of the household are aggregated for purposes of the annual tax computation. Combined assessments are due in principle if the spouses are not separated on the basis of a legal or judicial dispensation. Note that all taxpayers are not obligated/authorised to file an income tax return.
The annual tax return has to be filed before 31 March the year following the year the income is received. However, the 2023 Budget provides for an extension of the filing deadline to 31 December of the year following the tax year.
The annual WHT adjustment has to be filed before 31 December.
Payment of tax
Payroll income taxes are withheld by the employer on a monthly basis and may be regularised, depending on the circumstances, through an annual tax return or an annual WHT adjustment (décompte annuel).
The payment of income tax may be executed through instalments at the time the taxpayer files a tax return. These advances must be paid on a quarterly basis and are based on income tax paid in the previous year.
Statute of limitations
Luxembourg tax authorities have up to five years to require the payment of tax or the filing of the tax return.