You can't lock employees for another 2 years just by issuing one letter. It is very common employees tend to leave the company even after good increments. This is something inevitable. May be in the increment letter you may introduce 3 months increment reversal clause stating that in case of resignation within 3 months from the effective date of resignation, Management reserves the right to revoke the increment. The permanent solution is to identify the root cause behind this. Analyze your compensation packages for all levels whether the same is on par with market standards, whether congenial work environment prevails at your office etc.
You can't follow bonded labour system which was abolished long back.
From India, Madras
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