In the United States, the rating is issued by the Federal Aviation Administration.
[1] To be eligible to pursue an Instrument Rating, the applicant must:[2] A pilot must have an instrument rating in order to act as Pilot in Command of a flight below VFR weather minimums in controlled airspace (Class A, B, C, D, and E) and/or under IFR.
The rating is also required: Under FAR 61.57, to be eligible to fly in Instrument Meteorological Conditions (IMC) an IFR-rated pilot must accomplish and log at least the following IFR procedures under actual or simulated IMC every 6 months: An Instrument Proficiency Check administered by a CFII, DPE or ASI within the last 6 months is another way of complying with the IFR currency requirement.
If a pilot is not current looking back 6 months, they may complete the listed requirements in a flight simulator aviation training device or in an aircraft under simulated instrument conditions with a qualified safety pilot onboard.
If they are not current looking back 12 months, an instrument proficiency check is required.