You have taken right step.
On your DOJ company had 30+ employees, you have worked for 6Y, and you are eligible.
If company has not done compulsory insurance for Gratuity then you are not at fault.
You may write to good offices of appointing authority, MD that on dated Mr/Ms…………designation………….name of company …………address……………….stated during phone call (mention phone numbers)/in person/ etc………..that ………………………………(as posted by you)
And has not supplied the notice of determination of Gratuity…………………………….and you have supplied FormI to company by Redg. post receipt number …………………..dated………………….and it has been delivered on dated………………………..(attach screenshot of delivery report from www.indiapost.gov.in).................................and demand to supply the payment by bank DD by Redg. post only. YOu may mention that postage prepaid, self addressed envelope is attached for sending redg. post to you.
You may also obtain POD (free) and certified copy of run sheet of postman from PO (against Rs.10/)and if possible manage to obtain letter from sub postmaster that FormI (copy certified by sub postmaster) was packed in cover in his presence.
If company fails to supply the payment within 30 days from your date of relieving then you are entitled for interest @10%p.a.
It shall be better to transfer the PF and keep the a/c regular for atleast 10Y.
