I think that your query relates to your post-retirement service only. The issue of gratuity arises only on the termination of the post-retirement spell of your service under the same employer.From your inputs, it is discernible that your employment under the same employer continues but with a change in its mode i.e., from regular to contract basis only at the behest of the employer. I presume that the contract mentioned is probably a fixed term contract and not through any contractor. When your contract basis employment comes to an end, you are entitled to gratuity for the entire period of your post-retirement service as it would exceed the minimum qualifying service of five years under the same employer. As per the Madras High Court's judgment in Mettur Beardshell case which finds place in the discussions of this forum very frequently, even you are entitled to gratuity for the regular service of 4y+10m. Therefore, the contention of your management is not correct.If your employment stands terminated now, you can file a claim for gratuity for the entire spell of your post-retirement service before the Controlling Authority under the Payment of Gratuity Act,1972.