Dear Friend,
After retirement certainly some of the companies want the services of the retired employee on several counts. The payment will be as fees/honorarium/consultancy procedures/consolidated amount etc., some of the organisations deduct income tax accordingly. In your case better claim amount without mentioning gratuity, also, kindly verify you are not a regular in the regular service, if they have made yourself as a regular employee, you have the right to get all benefits of regular employment for these ten years. There is no interference of law in these services.
best of luck....