Hi Rajan,
Policy on Promotion will differ from company to company etc. I can give you some basic insights on what you can include in your draft, let me know if you need help in that? If yes, do share the following in detail
1. Industry that your company is into?
2. No of employees in the organization?
3. In case you have an existing Policy on Performance Appraisal and do share, it will help.
I may not be an expert in the field, but will try my best to assist.
Regards,
Anup