A single pension plan may be insufficient to sustain retirement life; however, people can immensely benefit from the National Pension System (NPS), which is open to all citizens, from government and corporate employees and self-employed to resident, non-resident, and overseas Indians, said Deepak Mohanty, chairperson of the Pension Fund Regulatory and Development Authority (PFRDA) in a speech on NPS at the ICC Conclave in Mumbai on Friday.