According to [ICAO][1], a preliminary report must be released after a year. There is no hard timeline for the full report:

>**What are a State’s reporting obligations during and after an aircraft accident investigation?**

>Under Annex 13 to the Chicago Convention, States in charge of an investigation must submit a Preliminary Report to ICAO within thirty days of the date of the accident, unless the Accident/Incident Data Report has been sent by that time. Preliminary Reports may be marked as confidential or remain public at the investigating State’s discretion.

>The State conducting the investigation of an accident or incident shall also make the Final Report publicly available as soon as possible and, if possible, within twelve months.

>If the report cannot be made publicly available within twelve months, the State conducting the investigation shall make an interim statement publicly available on each anniversary of the occurrence – detailing the progress of the investigation and any safety issues identified.

Keep in mind there is no established penalty for not complying with the above. Indeed [in some cases (or countries)][2] it can take up to a decade for a final report to be published.


  [1]: https://www.icao.int/about-icao/FAQ/Pages/icao-frequently-asked-questions-faq-11.aspx
  [2]: http://avherald.com/h?article=40fc7579/0002