Before you start

National register number
A determination of whether you are a Belgian tax resident
itsme or an eID card reader, to use MyMinfin
Your employer's assessment of whether the inbound taxpayer regime applies to you

Step-by-step

1
Establish whether you are a Belgian tax resident at all
Residence turns on where your home and centre of economic interests are, with registration in the population register creating a rebuttable presumption. Residents are taxed on worldwide income; non-residents only on Belgian-source income and file a different return. EU officials are deemed to keep their prior domicile under the EU Protocol and are a category of their own.
OnlineWho: You
2
Ask your employer about the inbound taxpayer regime before you start
Under the BBIB regime the employer can pay a portion of your gross remuneration as tax-free expense reimbursement. The regime is applied for by the employer within a short window after employment starts, and there is no route back if the window closes. Raise it at contract stage, not after the first payslip.
Via employerWho: Your employerAt hiring
3
Understand the four brackets and where 50% starts
For income year 2026, rates are 25%, 40%, 45% and 50%, with the top rate applying above roughly €48,000 of taxable income and a basic tax-free allowance around €11,180. Employee social security of 13.07% comes off gross before income tax. Belgium's total burden on employment income is consistently among the highest in the OECD.
OnlineWho: You
4
Check your commune's surcharge before signing a lease
FPS Finance publishes every commune's rate annually. For assessment year 2026 the nineteen Brussels communes run from 4.9% in the City of Brussels to 7.5% in Ixelles. The surcharge applies to the tax you owe, and it is your registered address on 1 January that determines which rate you pay for that year.
OnlineWho: You
5
File through MyMinfin, and watch the two deadlines
The return opens in late April for the previous income year. Paper returns are due end of June and online returns in mid-July, with a later autumn deadline for people with self-employment or complex foreign income. Many employees receive a proposed simplified return they only need to check — but checking it is still on you.
OnlineWho: YouLate April to mid-July
6
Report foreign accounts, insurance and property
Belgian residents must declare foreign bank accounts to the National Bank's central point of contact, and report foreign life insurance and foreign immovable property in the return. Since the 2021 reform, foreign property is valued on the same cadastral basis as Belgian property. This is one of the most commonly missed obligations among new arrivals.
OnlineWho: You

Documents you’ll need

National register number and itsme or eID reader
Annual payslip summary (fiche 281.10) from your employer
Records of foreign accounts, insurance policies and property
Mortgage, pension savings and childcare certificates for deductions
Any inbound taxpayer regime confirmation

Things most newcomers don’t know

The pre-2022 Belgian expat regime is gone, and the version that replaced it was rewritten again for 2025.

The special regime for foreign executives was abolished on 1 January 2022 and replaced by the inbound taxpayer regime (BBIB/RSII) and inbound researcher regime (BBIO/RSICI). For remuneration from 1 January 2025 the tax-free expense allowance rose from 30% to 35% of gross, the €90,000 annual cap on it was abolished, and the minimum gross salary condition fell from €75,000 to €70,000 — with researchers subject to no salary minimum. Social security did not follow: for contributions the 30% and €90,000 limits still apply, so payroll and tax now diverge. Most of what is written online describes either the abolished regime or the 2022–2024 version, and both are wrong for anyone moving now.

Source: FPS Finance; professional-firm circulars on the 2025 reform

Your commune sets a surcharge on your income tax, and in Brussels the spread is over two and a half points.

The additional communal tax is a percentage of the tax you already owe, voted by each commune and published by FPS Finance. For assessment year 2026 the City of Brussels charges 4.9%, Schaerbeek 5.0%, Uccle 5.6%, Etterbeek 5.8%, Saint-Gilles 6.3%, Anderlecht, Forest, Evere, Koekelberg and Molenbeek 7.0%, and Ixelles 7.5%. On the same salary, in the same region, ten minutes apart. Your address in the register on 1 January decides it, which makes the timing of a move between communes a small but real financial decision.

Source: FPS Finance — 2026 communal tax rates table

EU institution staff pay an EU tax and are not Belgian tax residents.

Articles 12 and 13 of the Protocol on the Privileges and Immunities of the EU exempt officials' institutional salaries from national income tax and deem them to keep their tax domicile in the country where they lived before taking up their duties, provided they moved solely for the job. They pay a progressive EU internal tax instead. This does not extend to Belgian-source income such as rent from a Belgian property, nor to a spouse's Belgian salary — and it is not the same thing as an expat tax break available to anyone else in the city.

Source: Protocol (No 7) on the Privileges and Immunities of the EU

The inbound regime is applied for by the employer, on a clock, and there is no second chance.

The employee cannot claim it unilaterally. The employer files within a defined period of the employment starting, and if that window closes the regime is simply unavailable for that engagement — which for a five-year benefit worth up to 35% of gross as tax-free reimbursement is an expensive administrative miss. Belgian HR teams that hire internationally know this; a first-time hiring manager may not. Ask explicitly during negotiation.

Source: FPS Finance

Common mistakes to avoid

Reading anything about the pre-2022 expat regime and assuming it still applies.
Letting the employer's window to apply for the inbound regime lapse unremarked.
Choosing a commune on rent alone without checking its surcharge rate.
Failing to declare foreign bank accounts, foreign life insurance or foreign property.
Assuming an EU-institution colleague's tax position tells you anything about yours.

Some of this may be out of date. Spotted something inaccurate? Help us keep it right for the next newcomer.