Merger by absorption: When to file corporate income tax?

In the context of a merger by absorption registered in the Commercial Registry during the 2025 fiscal year, the absorbing entity assumes the obligation to file corporate income tax returns for both its own activity and that of the absorbed entity for the current fiscal year. The income generated by the absorbed entity will be attributed to the absorbing entity, and its filing must follow the deadlines established in the Corporate Income Tax Law (LIS).

Registration in the Commercial Registry and tax subrogation

The registration of the merger in the Commercial Registry is the determining milestone for the attribution of tax obligations. The effects of registering these acts are retroactive to the date of filing of the deed documenting them, in accordance with Article 55 of the Commercial Registry Regulations.

From that date, the absorbed entity is legally extinguished, and the absorbing entity is subrogated to all of its rights and obligations, including those of a tax nature (Article 84.1 LIS). This entails the responsibility of the absorbing entity to file the corporate income tax returns corresponding to both entities.

Application of the tax neutrality regime

When the merger is subject to the special tax neutrality regime regulated in Chapter VII of Title VII of the LIS, there is no immediate taxation on the income generated as a result of the transaction. The application of the special tax deferral regime does not exempt either company from complying with the reporting obligations arising from the ordinary activities of both companies, both the acquiring and the acquired.

What must the absorbing entity declare?

In the case of a merger formalized and registered in 2025, the absorbing entity must submit:

1. The corporate income tax return of the absorbed entity, corresponding to the period between the start of the 2025 fiscal year and the date of registration of the transaction in the Commercial Registry, at which time it is legally extinguished.
2. Its own income tax return, including in its tax base: (i) income derived from its own activity throughout the fiscal year; (ii) income obtained by the absorbed entity from the beginning of the fiscal year until the date of its legal termination (registration of the merger), in accordance with the accounting and tax retroactive regime if so established in the merger deed.

In both cases, it is the absorbing entity that must assume formal responsibility for filing, consolidating the tax data of both companies.