From UK CAA CAP371:
A flight crew member is required to inform anyone who employs his services as a flight crew member of all flight times and flying duty periods undertaken, whether professionally or privately, except for flying in aircraft not exceeding 1,600 kg maximum weight and not flying for the purpose of public transport or aerial work.
Aerial work includes flying instruction for which the pilot is remunerated. It is also aerial work where valuable consideration is given specifically for flying instruction, even if the pilot receives no reward.
Don't know about your regulations but the UK CAA includes any hours flown in aircraft over MTOW 1,600 Kg as part of your annual FTL. A few companies in the UK explicitly prohibit their pilots from flying anything else privately or otherwise. Best you ask?