Taking Daniel's answer into account, yes, principal actors will likely be salaried.
Day Players & Supporting Artists [SA's] on the other hand, are usually paid by the hour, so any additional time spent in makeup is simply a part of their contracted day.
The rules are different for UK/US & presumably other countries, but essentially, their day is 9 hours, including a 1-hour meal break. Any time after that is paid at overtime rates [time & a half]
Early call is paid if they need to attend before 6am & night-rate overtime is paid up to 6am, when the 'day' starts.
If there is no other consideration then overtime would again start at 3pm, until they sign off at the end of the day.
All hours in attendance are paid in the same way, whether they are in makeup/costume, travelling from base to set, merely waiting off set [in a green room or bus/trailer] or actually participating in a scene.
The 9-hour day is a guaranteed rate, even if you are in attendance for less than that. [Unless booked as a shift call which is 4 hours]
Day Players [small parts, or only required for one or two scenes] may be paid on either a salary or hourly basis, depending on their negotiated contract.