I was in Assurance services previously but i can tell u that TP requires you to know in-depth company's taxation+ transaction. TP can be confusing since it covers related party transactions which can be extremely complex for big corporations. If you dont know the basic accounting for consolidation+inter co. transactions, u might not be able to cope with this TP.

Just my 2 cent.

in EY and PWC, if you dont have professional cert, u cant go beyond assistant manager level. Compulsory to have.