Living in Belgium with Spanish freelance income: where is it taxed for income year 2025?

A Belgian treaty resident generally pays Belgian tax on salary for work performed in Belgium and on independent professional income without a fixed base in Spain. Spanish registration or withholding does not automatically make that income exempt in Belgium; correcting the Spanish return may be necessary. The answer depends on the individual situation.

Figures below are illustrative; this article concerns income year 2025, Belgian assessment year 2026, with separate references to earlier years where relevant.

Tax residence comes before the tax return

Consider a professional who lives in Belgium, receives a Belgian salary and also invoices a Spanish business. A Spanish resident return has already been filed. The starting point is not how to transfer figures between forms: it is whether that resident return reflects the person's actual tax residence.

Belgian law contains a rebuttable presumption of residence for people registered in the National Register. The location of the household can also matter for married taxpayers, subject to the rules on separate assessment.

Spanish residence rules examine presence for more than 183 days in the calendar year, the main centre of economic activities or interests, and a rebuttable family presumption involving a spouse who is not legally separated and dependent minor children. Spending more days in Belgium than Spain is useful evidence, but it is not a substitute for applying the Spanish counting rules and examining the other criteria.

Where both countries claim residence, article 4 of the Belgium–Spain convention of 14 June 1995 applies successive tests:

• A permanent home available to the taxpayer.

• The centre of vital interests, if a home is available in both countries.

• Habitual abode.

• Nationality, if the earlier tests do not resolve the conflict.

A family address in Spain requires a factual examination: ownership is not the only question, because a home can be available without being owned. Equally, Spanish autónomo registration does not, on its own, establish Spanish tax residence.

Belgian salary and Spanish invoices follow different treaty provisions

Under article 15, salary for employment physically exercised in Belgium by a Belgian treaty resident is generally taxable in Belgium. The Spanish residence position must therefore be settled before applying Spain's worldwide-income calculation or foreign-tax credit.

Independent professional services follow article 14. For a Belgian treaty resident, Spain's taxing right depends on a fixed base habitually available in Spain, and extends only to income attributable to that base.

A registration address printed on an invoice does not by itself establish a fixed base. A regularly used office or workspace can change the analysis. Travel days, the location of actual work and the use of premises all matter.

If there is no qualifying Spanish fixed base, Spanish withholding does not create one. If there is such a base, an allocation may be necessary, with Belgian exemption with progression for the income that Spain may tax under the treaty. That allocation is not automatically the same as the percentage of days spent abroad.

Gross receipts, social contributions and expenses must remain separate

For independent professional income falling within Part 2, frame XVIII, the assessment-year-2026 form distinguishes:

For example, receipts of about €28,000, subject to 15% Spanish withholding, produce withholding of about €4,200. The receipts are still about €28,000 for the gross-receipts entry; the amount transferred to the bank account is not the starting figure.

Assume separately that deductible social contributions are about €1,400 and documented other costs about €700. The choice between actual expenses and the statutory allowance requires a calculation under the rules for the relevant Belgian income category.

The 30% allowance capped at €5,930 for income year 2025 is identified in the cited FPS Finance guidance for employee remuneration. It should not simply be carried across to liberal-profession profits. Likewise, Spain's 5% allowance for difficult-to-substantiate expenses is not automatically a Belgian deduction. A reliable net-profit estimate requires checking the correct Belgian expense regime.

The foreign-income section at the end of frame XVIII, rubric 16, concerns income qualifying for foreign-income relief. An overseas customer or foreign withholding alone is insufficient to claim that relief.

Paying tax in Spain does not automatically produce a Belgian credit

The decisive distinction is between tax charged in accordance with the treaty and tax charged under an incorrect residence classification.

For the professional-income scenario described here, Belgium may tax income fully where Spain has no treaty taxing right. The remedy for an undue Spanish charge is then sought in Spain, rather than by claiming an unsupported Belgian exemption.

Tax and social contributions must also be reconciled separately. Spanish invoice withholding, quarterly tax payments and the final income-tax balance can be components of the same liability. Social contributions do not become refundable income tax merely because the residence position changes.

An illustrative Spanish tax liability of about €7,000 therefore does not establish either a €7,000 Belgian credit or a guaranteed €7,000 refund. The remaining Spanish-source income and the payments actually made must first be checked.

Correcting the Spanish resident return

The source analysis identifies the rectification procedure under article 120.3 of the Spanish General Tax Law, together with articles 126–129 of the implementing procedural regulation, for a return challenged on treaty grounds.

A coordinated review normally examines:

• A Belgian tax-residence certificate, form 276conv, covering the relevant year and treaty position.

• Accommodation, work and travel evidence supporting residence.

• The Belgian return and the Spanish tax calculation.

• Modelo 030 for tax-domicile information.

• Whether Modelo 210 is required for income remaining taxable in Spain as non-resident income.

Where independent income is attributable to a Spanish fixed base, the source describes a 19% non-resident rate for an eligible EU resident and directly related expense deductions under article 24.6 of the Spanish non-resident income-tax law. Establishing the taxable base remains essential.

The source also mentions Spain's foreign-employment exemption of up to €60,100. That is a separate question for a person correctly treated as Spanish resident and meeting the exemption's conditions; it does not settle treaty residence or justify retaining an incorrect resident return.

A rectification request should not be assumed to suspend an outstanding payment automatically. Any instalment falling due, including a scheduled November 2026 instalment, requires separate attention.

Investment income, foreign accounts and property need their own review

Interest and dividends

The analysis distinguishes foreign interest potentially reportable under code 1444 at 30% from dividends eligible for the Belgian €833 exemption per taxpayer for income year 2025. Eligibility depends on the nature of the income; the exemption should not be assumed to cover every investment distribution.

The source refers to the Spanish exemption for qualifying interest received by EU residents without a Spanish permanent establishment under article 14.1.c of the non-resident income-tax law. For Spanish-source dividends, it identifies a 15% treaty rate in the individual-investor scenario.

The bank account's country does not, by itself, establish the source country of every investment payment. The instrument, payer and withholding must be examined. A later refund of foreign withholding can also affect the Belgian amount to report.

Occasional referral payments or rewards require a separate classification. The source discusses code 1200 for occasional miscellaneous income, while recognising uncertainty; this is not a blanket instruction to treat every banking promotion as taxable miscellaneous income.

For gains realised in 2025, the analysis concerns transactions within normal private asset management. Its conclusion should not be extended to speculative or professional activity, or to gains from 1 January 2026 without reviewing the rules for that year.

Foreign bank accounts

Code 1075, in frame XIII, concerns foreign accounts. An account can require reporting even with a zero balance. Reporting to the National Bank of Belgium's Central Point of Contact is separate from the annual return and must be addressed by the applicable filing deadline.

A genuinely Belgian account is not declared as a foreign account merely because the banking group operates internationally. Codes 1076 and 1077 concern foreign life insurance and legal arrangements, respectively; they are not substitutes for account reporting.

Spanish property

Staying in a relative's home does not automatically create reportable property income. Ownership or another relevant real right changes the position.

The source describes the Belgian cadastral-income system for foreign property, applicable since 2021, with notification within four months of acquisition. For relevant property not rented out, code 1106 and the foreign-property relief section can be involved. Treaty exemption with progression is distinct from having nothing to declare.

Salary and family-status codes are not a universal checklist

The source identifies these additional Belgian form entries, whose relevance depends on the taxpayer's documents and circumstances:

For assessment year 2026, personal status on 1 January 2026 and the year of separation can affect the return. The source explains that de facto separation generally leads to separate assessment from the following year. Cross-border spouses require additional analysis rather than copying another taxpayer's codes.

Social security and VAT do not decide income-tax residence

An A1 certificate under article 12(2) of Regulation 883/2004 can maintain the sending state's social-security legislation for a qualifying temporarily posted self-employed person. Its dates and conditions matter. A gap before the certificate's coverage requires review; paying contributions abroad alone does not resolve it.

VAT is a separate issue. In the general business-to-business services scenario described in the source, a provider established in Belgium serving a Spanish business customer may need to invoice under the reverse charge, rather than charging Spanish VAT at 21%. Establishment, customer status and the nature of the service must first be established.

Cessation of Spanish activity also requires checking tax and social-security deregistration. The source refers to Modelo 036 or 037 and RETA; the form available and applicable at the cessation date must be verified.

Why the final tax bill needs a separate calculation

The 2025 parameters quoted in the source are 25% up to €16,320, 40% from €16,320 to €28,800, 45% from €28,800 to €49,840, and 50% above €49,840, with a basic tax-free allowance of €10,910. These are marginal brackets, not a single rate applied to all income.

Communal tax is an additional component. An illustrative 6%–7% surcharge is not a Belgium-wide rate; the relevant municipality and assessment year must be checked. The employee allowance of 30%, capped at €5,930, and any independent-profession allowance must be computed under their respective rules. The special social-security contribution must not simply be treated as another deductible business expense.

Filing, correction and review periods

The source identifies 16 October 2026 as the Belgian online deadline for qualifying returns with specific income. Eligibility for that extended deadline must be confirmed for the particular return.

For Spanish rectification, it describes a four-year period from the end of the filing period, giving 30 June 2030 for the 2025 return and 30 June 2029 for the 2024 return, subject to the applicable procedural rules and any events affecting limitation.

Earlier years require their own residence analysis. A conclusion for 2025 does not automatically settle 2023 or 2024. Government-service remuneration can fall under article 19, rather than the ordinary employment rule; relevant exempt salary may require frame IV and its foreign-income section, rubric O, 2.

The source discusses a three-year Belgian assessment period, corresponding to 31 December 2028 for income year 2025 and 31 December 2027 for income year 2024. These should not be treated as universal cut-off dates: the applicable assessment rules and any longer periods must be checked. Similarly, the source's 10%–50% tax-increase range is not an automatic penalty prediction.

Its reference to an assessment by 30 June 2027 is not a guaranteed issue date for every case. Keeping residence evidence, invoices, A1 documentation and assessments for at least ten years, as recommended in the analysis, helps preserve the evidence needed for a coordinated review.

Frequently asked questions

Do I still pay Belgian tax if my Spanish client withheld 15%?

Possibly. Spanish withholding does not establish a treaty taxing right or automatically create a Belgian exemption. Residence and any Spanish fixed base determine the professional-income treatment.

Does being registered as an autónomo make me Spanish tax resident?

Not by itself. Domestic residence criteria and, where necessary, the treaty's residence tests must be applied to the facts.

Should I declare the net amount received from Spain?

For receipts reportable under code 1650, the starting amount excludes VAT but precedes Spanish income-tax withholding and expenses. Deductible contributions and expenses are considered separately.

Is a room at a family address a fixed base?

Not automatically. A permanent home for residence purposes and a fixed base for professional activity are different concepts; availability and actual use must be examined.

How much extra Belgian tax will I pay?

There is no single amount. The result depends on taxable income, the correct expense allowance, personal circumstances, payroll withholding and communal tax; a Spanish refund is a separate calculation.

Is a Spanish refund automatic after I file in Belgium?

No. The Spanish position generally requires a separate correction process supported by residence evidence, while any income still taxable in Spain must be addressed.

Sources

1. Belgian 2026 filing deadlines, 16 October 2026 for returns with specific income (Degand and Partners) - https://blog.degandpartners.com/fr/article/declaration-ipp-2026.-tax-on-web-ouvre-cette-semaine-et-les-changements-sont-multiples-decodage./31051

2. Income Tax Code 1992, article 2 (residence and National Register presumption) - https://finances.wallonie.be/files/NOSTRA/textes%20legaux/code%20des%20impots%20sur%20le%20revenu%20-%20exercice%202022.pdf

3. Spouses may have distinct tax residences (Forum for the Future) - https://blog.forumforthefuture.be/fr/article/deux-epoux-peuvent-avoir-des-residences-fiscales-distinctes/22996

4. Spanish tax agency, habitual residence in Spain, article 9 of the IRPF Law - https://sede.agenciatributaria.gob.es/Sede/ayuda/manuales-videos-folletos/manuales-practicos/irpf-2024/c02-irpf-cuestiones-generales/sujecion-irpf-aspectos-personales/residencia-habitual-territorio-espanol.html

5. Spanish residence criteria and the effect of a foreign residence certificate (Consejo General de Gestores Administrativos) - https://www.consejogestores.org/noticias/residencia-fiscal-espana-irpf-criterios-183-dias/

6. Belgium-Spain double taxation convention of 14 June 1995, full text (etaamb) - https://etaamb.openjustice.be/fr/loi-du-10-aout-1998_n2003015145.html

7. Belgian preparatory document 2026, Part 2, frame XVIII (SPF Finances) - https://fin.belgium.be/sites/default/files/media/documents/doc-preparatoire-partie-2-2026.pdf

8. Declaring liberal profession income: codes 1650, 1656 and 1657 (UCM) - https://www.ucm-bw.be/news/la-declaration-ipp/

9. Professional income and employee flat-rate expenses for income 2025 (FPS Finance) - https://fin.belgium.be/fr/particuliers/declaration-impot/revenus/revenus-professionnels

10. Regulation 883/2004, applicable legislation and posting of self-employed persons (CLEISS) - https://www.cleiss.fr/reglements/883_legislation_applicable.html

11. Exemption of interest received by EU residents under article 14.1.c of the Spanish non-resident tax law (DGT ruling) - https://www.fiscal-impuestos.com/sites/fiscal-impuestos.com/files/NFC073418.pdf

12. Rectification of IRPF self-assessments, article 120.3 LGT and the four-year period (Supercontable) - https://www.supercontable.com/informacion/impuesto_renta_IRPF/Rectificacion_de_autoliquidaciones_del_IRPF..html

13. Belgian certificate of tax residence 276conv via MyMinfin (SPF Finances) - https://fin.belgium.be/fr/particuliers/international/attestation-residence-fiscale

14. Deduction of expenses by EU residents under article 24.6 of the Spanish non-resident tax law - https://www.fiscal-impuestos.com/sites/fiscal-impuestos.com/files/NFJ092719.pdf

15. Real estate abroad: cadastral income, code 1106 and exemption with progression (SPF Finances) - https://fin.belgium.be/fr/particuliers/habitation/revenus-immobiliers/etranger

16. Foreign accounts, code 1075 and the Central Point of Contact (Test Achats) - https://www.test-achats.be/argent/impots/news/compte-a-l-etranger

17. Separated in fact but not yet divorced: codes and assessment (SPF Finances) - https://fin.belgium.be/fr/particuliers/declaration-impot/situation-personnelle/separation/separation-de-fait

18. Progressive tax brackets for income 2025 (Xerius, Fisc en poche 2025) - https://media.accdesk.be/sites/accdesk/files/documents/2025-04/fisc-en-poche-xerius-2025.pdf

19. Main personal income tax thresholds for assessment year 2026, tax-free allowance of 10,910 euros (Wolters Kluwer) - https://assets.contenthub.wolterskluwer.com/api/public/content/2593615-fiscale-grensbedragen-frans-jef-wellens-fadfadea3a

20. Belgian assessment periods after the law of 20 November 2022, article 354 CIR 92 (LDT Law) - https://www.ldtlaw.be/fr/news/documents/consult/121

This article explains a general framework and is not a personalised tax opinion. Rules and thresholds can change each year; the correct treatment depends on the exact facts, documents and applicable procedures.

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