You can have systems where you never actually do a renewal per se, just 3 checks a year, in that instance your instrument is invalid once you resign.
If you company actually does a 'instrument rating' check and treats it as a renewal then that's just as per normal and your rating will be current for 12 months.
Hypothetical question. If a CPL pilot obtains his initial issue command instrument rating in a two-crew certified aircraft type eg Saab 340, Dash 8, A320 etc, - does this also automatically qualify him to to fly in command single pilot IFR in (say) a Duchess, Chieftain etc if he has never previously flown a single pilot (ME) type before? Or is he required to undergo a single pilot (ME) additional instrument rating test?
To answer the original question no you can fly single pilot IFR even if your rating was in a multi crew aeroplane, however you have to be IFR current so your 3 hours IF has to be in your type of operation. So if you do 3 hours IF in a SAAB then go jump in a Kingair you may not be IF current