Overseas Citizens of India (OCI) cardholders, aged 18-70, can invest in the National Pension Scheme (NPS) on either a repatriation or non-repatriation basis. Contributions must be made through NRE/NRO accounts, with NRE accounts recommended for those wanting to remit funds back to their country of residence. But if an NPS subscriber has given up on their Indian citizenship and hasn't yet received or applied for an OCI card, they are not eligible to hold an NPS account.