Only requirement is to have written the Instrument Rating Exam.
To qualify for the IF rating, you will need to complete 40 hours of Duel IF Training with an instructor. Twenty of these hours may be completed in a FSTD approved simulator and twenty hours must be done in the aircraft. Here you will learn how to fly procedures, how to read IF plates and how IMC flying differs from VMC.
Once you are ready to take your simulator training to the aircraft, you will go out and fly actual Instrument Approaches and procedures to put the knowledge into practice. There are many aspects to the IF flying. Some of these include Aircraft Instruments, Aerodynamic factors, Human factors, Airplane attitude flying, Navigation Systems, Airspace, Air Traffic Control and collision avoidance, Emergency operations and much more.
When your training is complete, you will fly a test flight with the Designated Flight Examiner. This test involves the practical fligh test but also a verbal test where scenarios are set up for you to interpret according to the aircraft you are going to fly.