Variable Pay Letter Format

i am looking for a letter format which talks of variable pay...This will be part of the increment letter...
Something like.....
In addition to the revision above, you will be eligible for a variable pay as decided by the company every year. The variable pay for FY '15 will be communicated to you separately.
Then in a separate letter there needs to be a mention of the payment schedule and a mention that 'The payment schedule above is indicative and is subject to quarterly decisions taken based on performance by the company'.
Can anyone share a IT company's variable pay letter format
Rgds
Rekha

Hi Rekha,
just see if this will help you.
«Gender». «EMPLOYEE_NAME»
Emp Code: «EMP_No»
We are happy to inform you that you would be eligible for Rs. ...... as Variable pay.
Payable monthly / quarterly / annually subject to the achievement of mutually agreed KRAs ( you can probably incorporate the eligibility criteria here).
All the other terms and conditions remain unchanged.
Wish you all the success!!
For ................
Name
Designation