DLU quinquies is Belgium's permanent tax regularisation procedure. A taxpayer volunteers income or capital that was never taxed, pays a flat surcharge, and receives a certificate protecting them from tax claims and criminal prosecution on the declared amounts. It reopened in summer 2025 after a gap that began on 1 January 2024. It deals with the past; it does not structure anything for the future.
Legal basis: the programme law of 18 July 2025. Rates: normal tax plus 30 percentage points on income that is not time-barred, and 45% on fiscally time-barred capital. In return: tax and criminal immunity, limited to federal taxes and to the person who files.
A permanent window, reopened in summer 2025
The scheme rests on the programme law of 18 July 2025 and a royal decree of 28 July 2025 that sets the forms. It follows DLU quater (law of 21 July 2016). Since 1 January 2024 there had been no legal framework for regularising at all. Unlike earlier rounds, which were time-limited, this one is designed to stay open.
Filing is voluntary and spontaneous. It is open to individuals who are Belgian tax residents and to companies and other legal entities established in Belgium, and it goes through the Regularisation Contact Point of the Federal Public Service Finance. It covers income that is not yet time-barred and capital that is fiscally time-barred: foreign accounts, unreported professional income, overlooked movable or immovable assets, mishandled gifts or inheritances, concealed insurance contracts.
Two rates, depending on what is being declared
| Type of amount | DLU quinquies | For comparison: DLU quater |
|---|---|---|
| Income not yet time-barred | Tax at the normal rate + 30 percentage points | 25% surcharge |
| Fiscally time-barred capital | Separate charge of 45% | 40% |
Time-barred capital is capital on which the tax authority can no longer exercise its collection power against the taxpayer who committed the infringement. Legislators have therefore raised the bill by roughly five points compared with 2016.
Two simplified illustrations. Time-barred capital of EUR 100,000 costs EUR 45,000. Undeclared income of EUR 100,000 that would have been taxed at a normal rate of 30% costs EUR 30,000 in tax plus EUR 30,000 in surcharge, EUR 60,000 in total. The real figure depends on the normal rate that applies under the Belgian Income Tax Code and on the nature of the income, and is worked out file by file.
The burden of proof sits with the filer
This is the point most often underestimated. The filer must show in writing that the amounts submitted have not already borne their normal tax treatment, and in principle has to regularise the whole body of assets presented unless they can prove that some items were already taxed. For old capital that proof is often impossible, which is precisely why the flat 45% exists.
In practice, preparation takes longer than the procedure itself. Statements for the accounts involved have to be rebuilt, significant movements traced, the documents explaining where the funds came from gathered, and the income that stayed outside tax returns quantified year by year. A coherent file also removes any suspicion of criminal origin, which matters as much as the rate calculation.
The file describes the origin and amount of the funds and includes an overview of the financial accounts used. Immunity covers what was declared and nothing more. The declaration should therefore be prepared with an adviser, with supporting documents, before anything is filed.
What regularisation does not cover
Four limits come up with every practitioner. The framework is federal: inheritance and gift taxes, which are regional, fall outside it. Immunity benefits only the person filing, not intermediaries, beneficiaries or co-owners. The route is closed to anyone who has been informed in writing of specific ongoing investigative acts, whether by the judicial authorities or the tax administration. Funds of criminal origin are excluded. Anyone wishing to use the procedure must therefore be able to explain where each declared amount came from, and must not already be the subject of an investigation of which they were notified in writing.
The more favourable treatment announced for heirs acting in good faith did not make it into the final text. An heir who discovers undeclared assets left by a parent pays, in principle, the same rates.
Once the calculated tax is paid, within a short window of about fifteen days according to practitioners, the filer receives a certificate. It protects against tax reassessment of the regularised amounts and against prosecution for tax fraud and money laundering linked to those amounts.
Regularising is not structuring
Regularisation puts a patrimony in order; it does not optimise how that patrimony is held. Once declared, the amounts are visible to the tax authority and taxed normally going forward. Some Belgian banks also refuse capital that has not been regularised, which is a practical reason to regularise before any major wealth transaction.
For anyone considering buying artworks, using a movable-asset lease or planning a transfer, the order of operations matters. An artwork launders nothing and does not stand in for regularisation: it presumes that the origin of the funds is documented. Regularise first, structure second, and only then price the options (liquidation reserve, payment in kind, gift) from a clean starting point.
Frequently asked questions
What is DLU quinquies and who can use it?
It is the permanent tax regularisation procedure introduced by the programme law of 18 July 2025. It is open to individuals who are Belgian tax residents and to legal entities established in Belgium, through a voluntary declaration filed with the Regularisation Contact Point of the Federal Public Service Finance.
How much does a tax regularisation cost in 2026?
For income that is not time-barred, tax is computed at the normal rate and increased by 30 percentage points. For fiscally time-barred capital the charge is 45%; for comparison, DLU quater applied a 25% surcharge and a 40% rate.
What protection does regularisation give?
Once the tax is paid, the filer receives a certificate protecting them from tax reassessment and from prosecution for tax fraud and money laundering relating to the declared amounts. That immunity is federal: it does not cover regional inheritance taxes, intermediaries or co-owners, or taxpayers who were already notified in writing of an investigation.
The first meeting is for checking whether your situation falls under regularisation and in what order to handle what follows, not for selling a structure. It does not replace the advice of a tax lawyer or certified accountant on the file itself.