For JAA/EASA license holders operating outside the EASA system unaware of this issue please take note.
Under the EASA regulations after 7 years without a renewal you will be required to sit all 7 ATPL exams relating to an IR before the Skills Test.
There is no allowance for operations under any other ICAO authorities.
CAP 804: Flight Crew Licensing: Mandatory Requirements, Policy and Guidance | Publications | About the CAA
CAP 804 Part G Subpart 1 3 Requirements
FCL.625 IR(A) - Validity, revalidation and renewal
(d) If the IR(A) has not been revalidated or renewed within the preceding 7 years,
the holder will be required to pass again the IR theoretical knowledge
examination and skill test.
FCL.615 IR(A) - Theoretical Knowledge Examinations and Flight Instruction
(b) Examination. Applicants shall demonstrate a level of theoretical knowledge
appropriate to the privileges granted in the following subjects:
— Air Law,
— Aircraft General Knowledge – Instrumentation,
— Flight Performance and Monitoring,
— Human Performance,
— Meteorology,
— Radio Navigation,
— IFR Communications.