Do promotions and pay rises still happen in March or is there only one round in September?

It depends on the company concerned.

The clue I think was in the name ACN

Yes, I meant Accenture, sorry for not making it at all clear!

Accenture always had and will have 2 rounds: the big formal always there opportunity at the 1st of September. There is always a lot of BS about the round in March. It does exist, but not always they'll admit it and keep it very limited (to explicitly retain certain people who'd else walk away).

the march 2010 promo round was widely circulated and several managers who were held back in sep 09 came in all at once. bit of a nightmare really but I agree it's all a bit dependent on the reward / retention strategy of the moment.

the march 2010 promo round was widely circulated and several managers who were held back in sep 09 came in all at once. bit of a nightmare really but I agree it's all a bit dependent on the reward / retention strategy of the moment.

So basically the March round happens in good times? But only the September round (if any promotion rounds) in the bad times?

More or less, although there are no pay rises in March - only promotions.

To be clear, march promotions will be given their payrise in march. non-promotion ratings (even VT) will not result in a payrise until september.