How often do indoor kittens/cats need to be vaccinated?

My kitten will be getting his final vaccine in August (he'll be 4 months old). but after that how often should i take him to the vet for vaccines and how many vaccines would be need every time?

i read somewhere that rabies vaccine should be given every year. is that true? 

We give our cats yearly vaccinations, but the vet now gives them fewer different vaccinations than at the beginning. They get yearly rabies, and something else I'd have to look up. It's their belief that they should get fewer vaccinations rather than piling them on just in case. My cats are indoor, get regular vet care, and have has a lot of vaccs when younger so all this is a consideration for the vet.
Regarding rabies, a lot of municipalities require it. But there is now the three year vaccination, and a lot of people think the protection is actually longer than that so they don't repeat it that often.

IMO, the most important thing is an annual wellness check, not annual vaccines.  An FVRCP does not need to be repeated annually, again, my opinion.  I would do an annual booster the first year, then maybe every 3 or so years.  First rabies is a one year shot, after that, they can be given every 3 years.  If your state requires rabies vaccines then you do need to do them, unless you and/or your vet believe that it is a serious health risk.  Vet can write a waiver, or your state may accept titer results proving that the cat still has immunity against rabies. 

In my area there are a fair amount of bats.  They can and do carry rabies and sometimes get stuck in houses.  So I still keep my indoor-only cats on a strict rabies vaccine schedule because if they were attacked by a rabid bat--nothing to do for them.  Similarly, the local HS is pretty strict about rabies quarantine.  If one of my cats got out and got lost and wound up at the local HS as a stray, I would face a large fine (eh) but also a 10 day quarantine for the cat unless I could prove it was up to date on rabies vaccines.  I don't want to think about one of my cats languishing in a kennel under a rabies quarantine at that place. 

It's scare tactics to a certain extent, yes, but I think the rabies vaccine is well worth it.  FVRCP, once a kitty has decent immunity from kittenhood plus one adult booster, is probably something you can give sparingly.  I think the current advice is every 3 years as an adult.