Under Article 571 of the Turkish Civil Code, the right to file a reduction (tenkis) action lapses one year after the heirs learn that their reserved share has been infringed, and in any case ten years after the will was opened (for testamentary dispositions) or after the estate was opened (for other dispositions).
These are preclusive periods, not statute-of-limitations periods, and the court applies them ex officio. Learning about the infringement before the estate is opened does not cause the period to start running earlier.
A reduction claim can also be raised as a defense at any time, without being subject to this time limit.