ITC on office rent when landlord is unregistered — can we claim?

AY context: FY 2025-26, registered regular taxpayer (services), Delhi. Facts: - We pay monthly office rent to an individual landlord who is not GST-registered. - Rent is above the threshold where RCM often comes up in practice discussions. - Invoice from landlord is a rent receipt only (no GST). Questions: 1. Is GST payable under RCM on this rent, and under which notification / category? 2. If we pay RCM, can we take ITC in the same month (subject to Sec 16 conditions)? 3. Any common mistakes CAs should flag in working papers for this? Already checked: GSTR-3B RCM table and basic Sec 9(3) notes — want a practical confirmation for CA working files.