The Supreme Court clarifies how to calculate the main source of income in family business transfers

A significant judgment for family businesses

The Supreme Court has issued an important judgment for people planning to transfer a family business or economic activity without payment.

Judgment 827/2026 of 1 July 2026, appeal 2632/2024, examines how to determine whether an economic activity is the taxpayer’s “main source of income” when different income streams are calculated using tax methods that cannot be compared on a like-for-like basis.

The issue may appear to be merely mathematical, but it directly affects:

• The wealth tax exemption for certain businesses and business assets.

• The reduction available on transfers of family businesses for inheritance and gift tax.

• The absence of a capital gain for the donor under personal income tax.

• Planning gifts and succession of a business.

The Supreme Court concludes that, where income has been calculated using different methods and the net figures are not comparable, the comparison must use gross income, rather than net income alone.

Why does the main source of income test matter?

Article 4(8)(1) of the Wealth Tax Act allows certain assets and rights used in business or professional activities to be exempt.

Among other conditions, the taxpayer must carry out the activity habitually, personally and directly, and it must constitute their main source of income.

As a general rule, Article 3 of Royal Decree 1704/1999 treats an activity as the main source of income where at least 50% of the personal income tax base comes from the net income of the relevant economic activities. (Official Royal Decree 1704/1999)

This Wealth Tax requirement also affects other taxes.

When a person gifts a sole proprietorship, professional business or certain qualifying family-company shares, Article 20(6) of the Inheritance and Gift Tax Act may allow a 95% state-level reduction in the recipient’s taxable base.

In turn, Article 33(3)(c) of the Personal Income Tax Act provides that the donor has no capital gain or loss on qualifying gifts of businesses or shareholdings covered by that Article 20(6). (Official Personal Income Tax Act)

If the Tax Agency concludes that the activity is not the taxpayer’s main source of income, it may therefore deny all of the following:

• The Wealth Tax exemption.

• The Inheritance and Gift Tax reduction.

• Tax-neutral treatment of the gift for the donor’s personal income tax.

The case before the Supreme Court

The taxpayer had gifted his son certain assets used in an agricultural activity.

In the tax year under review, he received two main types of income:

• A retirement pension.

• Income from the agricultural activity.

The dispute arose because the result of the comparison changed completely depending on whether gross or net income was used.

Income	Gross income	Net income
Retirement pension	€8,471.40	€6,471.40
Agricultural activity	€9,653.11	€842.72

On a gross-income comparison, the agricultural activity produced more than the pension.

On a net-income comparison, the pension was clearly higher.

The Tax Agency considered that net income had to be used and denied the tax regime for the transfer of a family business.

The problem: figures calculated in different ways were being compared

The agricultural activity was taxed under the objective assessment method, while the pension income was determined under the general rules for employment income.

Under objective assessment, net income is not calculated simply by subtracting actual expenses from revenue.

Instead, it is calculated using modules, indices, indicators or parameters set by regulation.

By contrast, net employment income is calculated from gross income after deducting the expenses and allowances provided for in the Personal Income Tax Act.

As a result, two amounts formally called “net income” were being compared, even though they had been produced using radically different methods.

In the Supreme Court’s view, that comparison could give a distorted picture of the activity’s true economic importance.

The Supreme Court’s ruling

The Supreme Court held that, in deciding whether an economic activity is the main source of income for the purposes of Article 33(3)(c) of the Personal Income Tax Act, gross income must be considered where the income streams being compared were calculated using different methods that prevent a like-for-like comparison of net amounts.

In this case:

• The agricultural activity generated gross income of €9,653.11.

• The pension amounted to €8,471.40.

• In economic terms, the activity was the taxpayer’s largest source of income.

• Relying only on module-based net income artificially distorted that reality.

The judgment therefore upheld the Valencian Community High Court’s approach and dismissed the appeal brought by the Spanish State Administration.

The Supreme Court’s purpose-based approach

The Court did not limit itself to a literal reading of Royal Decree 1704/1999.

It also considered the purpose of the family-business tax regime.

The tax benefits for business transfers are intended to support the continuation of economic activities and to prevent the tax burden arising from an inheritance or gift from forcing the business to be split up, sold or stripped of capital.

According to the Supreme Court, comparing non-comparable economic figures could undermine that purpose.

It could also conflict with the ability-to-pay principle, because the tax benefit would depend on the technical method used to calculate income rather than on the activity’s actual importance in the taxpayer’s economic circumstances.

The judgment therefore seeks an economically coherent comparison, not merely one based on labels.

Does this mean gross income must always be used?

Not necessarily.

This point needs particular care.

The wording of the legal doctrine supports using gross income. However, the judgment’s reasoning is closely tied to a specific circumstance: the net figures being compared had been calculated by different methods and were not economically comparable.

It would therefore be unwise to read the judgment as requiring gross income to be used indiscriminately in every case.

Where the different income streams are calculated using comparable methods, the Tax Agency may continue to argue for a literal application of Article 3 of Royal Decree 1704/1999, which refers to net income.

The judgment opens an important interpretative route, but it does not automatically resolve every dispute about the main source of income.

The ruling should not automatically be extended to company shareholdings

The judgment concerns an economic activity carried on directly by the taxpayer.

This requirement should not be confused with the test for the exemption of shareholdings in companies.

For company shareholdings, there is a separate requirement: a member of the family group must perform management duties and receive remuneration for them exceeding 50% of that person’s employment, business and professional income.

The Supreme Court itself distinguishes the case before it from administrative decisions on how to calculate remuneration for management duties in companies.

Accordingly, the judgment does not automatically establish that gross amounts must always be compared when deciding whether a director’s remuneration exceeds the 50% threshold.

These are separate requirements, even though both form part of the family-business tax regime.

Who may benefit from this judgment?

The ruling may be particularly relevant to:

Farmers and livestock breeders using objective assessment

They are most directly affected because their net income may be calculated under objective assessment and may be far lower than their actual receipts.

Business owners who receive a pension

Where an economic activity coexists with a retirement pension, disability pension or other benefit, the pension may appear to be the main source of income if only net figures are compared.

The judgment requires an assessment of whether that comparison is genuinely like-for-like.

Professionals whose income is calculated under different methods

The ruling may also matter where a taxpayer receives employment income, business income under direct assessment and other income subject to objective assessment.

Gifts of family businesses

Before gifting a business, check that all the conditions in Article 20(6) of the Inheritance and Gift Tax Act are met.

The judgment may prevent the tax regime from being denied solely because module-based net income from the activity is lower than income from other sources.

Ongoing tax proceedings

Taxpayers involved in an audit, administrative tax appeal or court case on this issue may rely on the Supreme Court’s ruling.

It is also worth assessing whether any tax returns remain open to correction. The ability to claim will depend on the specific circumstances, existing administrative decisions and whether a final decision prevents the matter from being reopened.

Documents to keep

The judgment makes it more important to substantiate the activity’s economic reality.

It is advisable to keep:

• Personal income tax returns for the relevant years.

• Quarterly advance-payment returns.

• Business books and invoices.

• Pension certificates and employment-income records.

• Separate calculations of gross and net income.

• Details of the method used to calculate each income stream.

• Evidence that the activity was carried on habitually, personally and directly.

• Documents relating to the gift or business transfer.

• Evidence that the other family-business regime requirements are met.

It is not enough to show that the activity generated higher receipts. All other requirements under the Wealth Tax Act and the Inheritance and Gift Tax Act must also be met.

Legal assessment

The judgment is a positive development.

Comparing only net income can produce arbitrary results when each amount is calculated under entirely different rules.

Net income calculated under modules does not necessarily reflect the activity’s actual economic profit. It is a tax estimate.

Comparing it with a pension whose net amount is calculated under different rules can make a technical construct decisive in granting or denying substantial tax benefits.

The Supreme Court adopts an interpretation that is closer to economic reality and to the purpose of protecting family businesses.

However, the judgment also creates some uncertainty.

The wording of Article 3 of Royal Decree 1704/1999 still refers to net income. The reach of the new doctrine, and the circumstances in which calculation methods are not comparable, will need to be clarified.

The cautious approach is to apply the Supreme Court’s test where there is a genuine lack of comparability, while documenting:

• Gross income.

• Net income.

• The method used to calculate each income stream.

• The distortion that would result from comparing the net figures.

Conclusion

The Supreme Court has corrected an excessively formalistic interpretation of the main-source-of-income requirement.

Where a taxpayer’s income streams are calculated using different methods and their net figures cannot be compared, gross income must be considered to determine the activity’s true economic importance.

The judgment may make it easier to apply the family-business tax regime to gifts of sole proprietorships, particularly agricultural, livestock or other businesses taxed under objective assessment.

It does not, however, mean that all taxpayers may freely use gross income in every case.

The ruling must be applied to its specific circumstances and cannot automatically be extended to the requirements for company shareholdings or to cases where income is calculated using comparable methods.

This is a taxpayer-friendly judgment with implications for business succession planning and potential relevance to audits or tax returns that are not yet final or time-barred.