Commercial Fixed Wing
Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Confusion
Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural MEL / CDL
General None Reported / Taken
Environment - Non Weather Related; Human Factors; Company Policy; Procedure
Upon checking AML and release it was determined our aircraft required a CAT 2 confidence check. It was also noticed that the aircraft was CAT 2 MEL. As Captain I advised the FO that we would; given the opportunity; perform  our visual arrival into ZZZ as if it were a CAT 2 approach. We performed all the required procedures for the CAT 2. All went as planned and our aircraft passed all required pre-testing. The appropriate procedure was then followed to report completion of the required confidence check. It was then that I was advised that our confidence check was not authorized as the aircraft was still under a CAT 2 MEL. I was also advised that the CAT 2 MEL should not have been in place; but had not properly had that MEL removed.As a result of no associated MEL which would require a CAT 2 MEL; it was believed that it was directly related to a required confidence check. Lots of our aircraft have needed confidence checks to regain currency due to time in storage. I made this assumption incorrectlyPracticing advanced approaches in conditions not requiring  them only helps to build proficiency and confidence. The fact that the plane was not CAT 2 authorized had no effect on our approach as we didn't need to; nor did we; deviate from anything that would have occurred making any other ILS on Runway XL. In reality; the aircraft tested appropriately and if it hadn't that would have been noted and reported.
Air carrier Captain reported executing a CAT II confidence check approach which was not authorized.