I stand to be corrected.....
....and corrected you will be.
To give instruction for the IR, you must either hold an FI rating with the applied IF restriction removed or a stand-alone IRI rating. In both cases you must also hold a valid IR.
The only difference between the requirements for an FI to instruct for the IMC rating and the IR is the requirement to hold the rating for which instruction is given (i.e. the IR).
This, of course, relates only to the requirements in the UK