RG ARCA 5908/2026. BO 5/10
Through General Resolution 5908/2026, ARCA is implementing a new web-based service accessed through the Tax Key (Clave Fiscal) called “Corporate Income Tax”, which will progressively replace the traditional SIAP application (“Corporate Income Tax – Companies”) for the preparation and filing of corporate income tax returns by companies, trusts, and other entities that prepare commercial financial statements (taxpayers covered by Article 53 of the Income Tax Law).
The measure applies to companies, trusts, and other entities that prepare commercial financial statements.
The new service will be available through ARCA’s official website and is intended for the preparation and filing of corporate income tax returns for the taxpayers covered by Article 53, paragraphs (a), (b), (c), (d), (e), and the final paragraph of the Income Tax Law, provided that they prepare commercial financial statements.
The resolution establishes that the web-based service will apply to income tax returns corresponding to commercial fiscal year-ends occurring on or after June 2026, inclusive.
The transition to the new system is divided into two main stages:
- Optional stage (October 19, 2026, through February 28, 2027): During this period, taxpayers may choose to prepare and file their returns using the new web-based service or continue using the SIAP application pursuant to General Resolution 4626. The web-based service will be available starting October 19, 2026.
- Mandatory stage (beginning March 1, 2027): Once the transition period ends, use of the web-based service will become exclusive and mandatory for all fiscal year-ends from June 2026 onward.
Both original income tax returns and amended returns corresponding to commercial fiscal years closed before June 2026 must be prepared using the SIAP application.
For fiscal year-ends from June 2026 onward, amended returns must be filed through the same filing method used for the original return, whether through the SIAP application or the web-based service.
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