Question about getting salary raise if on Tier 2

Hey Immigration Board people.

I have permission to stay under Tier 2 (General) until April 2016. My employer is going to renew my visa.
I am here under SOC 2137 “Web design and development professionals”. When I first came to the UK on this visa, my rate of pay was 25200 for an “experienced” worker. My COS doesn’t have a salary range, just 25200. If I ask for a raise does my employer have to re do the RMLT? Is any raise possible without an RMLT?

Thanks

No RLMT required if only salary is changed.
RLMT is required if the role is changed and you apply with different SOC code.

Your employer can issue an increment letter and update the same through SMS.

Ok, so is an Increment letter something that is within the SMS and that my employer has to take care of?

Can you should me where the documentation is on the Internet about an increment letter, and where it says it is possible to get a raise?

Sorry I can't find it in the RMLT.

Thanks so much!

By increment letter, I mean a soft or hard copy where employer can state that your salary is incremented to £amount (e.g.) based on your performance or annual increment or something and same amount can be updated through SMS so HO will know the same. Cheers.