Alas, as always, the answer is not so simple. (And, as always, the persistent folklore that there was a passenger limit on cost sharing flights under the 'old' rules is just that - persistent.)
Under the 'new' oh-so-simple rules, the answer also depends on whether the registered operator of the aircraft is or is not an individual. So, before you go on a jolly as PIC with a private licence and a large bunch of mates, you need first to know whether the registered operator of the aircraft is a human or not. (We all look up the register to check whether the registered operator of the aircraft we hire is a human or a company, don't we?) Be careful if the registered operator of the aircraft is a corporate entity rather than you as an individual.
(1) A passenger transport operation is an operation of an aircraft that involves the carriage of passengers, whether or not cargo is also carried on the aircraft.
(2) Despite subclause (1), an operation is not a passenger transport operation if the operation is:
(a) an operation of an aircraft with a special certificate of airworthiness; or
(b) a cost‑sharing flight; or
(c) a medical transport operation; or
(d) if the registered operator of an aircraft is an individual—an operation of the aircraft:
(i) that involves the carriage of that individual; and
(ii) does not also involve the carriage of other passengers; or
(e) if the registered operator of an aircraft is an individual—an operation of the aircraft:
(i) that involves the carriage of that individual; and
(ii) involves the carriage of other passengers; and
(iii) for which no payment or reward is made or given in relation to the carriage of the other passengers or cargo.
And, Squawk, please let me know your view on the maximum number of passengers I can carry, as PIC with a private licence, on a Cessna 208:
- whose registered operator is a corporate entity, and
- whose registered operator is me as an individual.