What Did the First Filing Period Teach Us? Lessons from the 2024 Fiscal Year Implementation
The first year of implementation is now behind us. The process revealed that it was the timeline of the legislation — not its text — that proved problematic, and this carries concrete lessons for the period ahead.
Why Does It Matter?
The chaos of the first year is not a one-off; it is the natural consequence of a system maturing. But it will be harder in subsequent periods to justify the same gaps in preparation on the grounds of a "transition year." The stopgap solutions used in the first year need to be turned into permanent control mechanisms.
Lesson 1: The Legislation Was Clarified Only After the Filing
The General Implementation Communiqué was published on 26 December 2025. Yet the first local return for the 2024 fiscal year was due on 31 December 2025. In other words, taxpayers had five days left before the filing deadline when the communiqué setting out the implementation rules was published. Drafts of the return and notification form were only shared on 8 April 2026.
The lesson: don't wait for the legislation to be finalized before starting the calculation work. Data gathering and modelling can proceed independently of the communiqué.
Lesson 2: Deadlines Were Extended Repeatedly — But That's Not a Strategy
The local return deadline was extended twice: 31 December 2025 → 15 January 2026 → 28 January 2026. The global return deadline was moved from 30 June 2026 to 31 July 2026 by a circular published on the very last day.
The lesson: the extensions came not because of the system, but because of the volume of requests. It is risky to plan on the assumption that the authority will show the same flexibility in the second year.
Lesson 3: Even Non-Taxpayers Ended Up with Obligations
This was the most surprising aspect in practice: Türkiye-based entities that were not themselves global top-up taxpayers, but were affiliated with an in-scope group, still had to file the notification form and its accompanying general information form.
The lesson: "no tax arises" and "no obligation exists" are different things. The obligation map should be drawn up before the tax calculation.
Lesson 4: The Data Comes from Consolidation, Not from Local Accounting
The ETR calculation is not built from the tax base, but from the financial statements used for consolidation. Many Turkish companies discovered in the first year that this data was held at group headquarters and did not exist in their own systems. The time between requesting the data and receiving it stretched to weeks in many groups.
Why Should the First Year's File Be Reopened?
Having filed the first return does not mean every interpretation used has been settled. A subsequently published administrative guide, a correction made by group headquarters, an error surfacing in the financial statements, or an inconsistency in the information-exchange process may require the earlier filing to be reassessed.
The first year's file should contain: the scope determination, the safe harbour election, the ETR reconciliation, the link between the local and global filings, the exchange rates used, and management approval. The starting point for the second year's work is not to copy the previous filing, but to perform a gap analysis: group acquisitions, use of incentives, deferred tax movements, entity closures, and changes in safe harbour thresholds should each be tracked with a separate checklist.
Points to Note
"We got through the first year, so the second one will be easy."
On the contrary, the second year may be harder. UTPR takes effect starting from the 2025 fiscal year. The threshold for the simplified ETR test rises from 15% to 16%. And the authority now has the first year's data and is in a position to compare.
Action Items
- Archive the assumptions and rationale used in your 2024 filing — these will be the first thing requested if an audit arrives
- Start work on the 2025 fiscal year now; 31 December 2026 is not far away
- Set up a written request-and-delivery timeline in advance for data coming from group headquarters
- Recalculate whether you will pass the safe harbour test again this year, taking the rising threshold into account
- Use a gap analysis to check whether the interpretations used in the first year are still valid in the second
Conclusion
Revisiting the first year's filing is not merely an exercise in finding errors. It is what allows the assumptions used, the data sources, the safe harbour elections, and the internal approval process to be converted into a reusable compliance file for the second year.