Originally Posted by
extricate
I searched and found this in ICAO Annex 6
"4.3.6.5 A flight shall not commence unless the usable fuel on board meets the requirements in 4.3.6.3 a), b), c), d), e) and f) if required and shall not continue from the point of in-flight re-planning unless the usable fuel on board meets the requirements in 4.3.6.3 b), c), d), e) and f) if required."
where a: Taxi Fuel, b: Trip Fuel, c: Contingency Fuel, d: Destination Alt Fuel, e: Final Reserve Fuel
and ‘flight’ commences when you start to taxi therefore you can burn contingency in the taxi. At takeoff you need trip fuel, alternate fuel (if applicable, otherwise extra fuel as per no alternate procedures) and final reserve