| August 15, 1985 | Proposal for a Refinery Included in  "Assam Accord"  as a part of Government of India's offered economic package | 
| June 23, 1989 | IBP Co. Limited Appointed as Implementing Agency (Equity Structure IBP: 51%, Govt. of Assam: 10%, Public: 39%) | 
| May 31, 1991 | Environmental Clearance Obtained for Refinery Project | 
| August 28, 1992 | EIL Appointed as Prime Consultant | 
| July 3, 1992 | Foundation Stone for Refinery Laid by Prime Minister of India Shri P.V. Narasimha Rao | 
| July 15, 1992 | CCEA (Cabinet Committee of Economic Affairs) Approval for Implementation of Numaligarh Refinery Project | 
| April 22, 1993 | Numaligarh Refinery Limited Incorporated as a Company | 
| June 2, 1995 | BPCL Inducted as Major Promoter (Equity Structure BPCL: 32%, IBP: 19%, Govt. of Assam: 10%, Public: 39%) | 
| April, 1999 | Numaligarh Refinery Commissioned | 
| July 9, 1999 | Numaligarh Refinery Dedicated to the Nation by Prime Minister of India Shri Atal Bihari Vajpayee | 
| October, 2000 | Commencement of Commercial Operations | 
| March, 2001 | NRL Becomes Subsidiary of BPCL (Equity Structure BPCL: 61.65% ; OIL: 26% Govt. of Assam: 12.35%) | 
| October 22, 2018 | Public Investment Board (PIB) Clearance for Refinery Expansion from 3 MMTPA to 9 MMTPA | 
| January 16, 2019 | Cabinet Committee of Economic Affairs Approval for Refinery Expansion Project at a Project Cost of Rs. 22,594 Crore | 
| July 27, 2020 | Environmental Clearance Obtained for Refinery Expansion Project | 
| March 25, 2021 | BPCL Exits NRL as Major Stakeholder. OIL Acquires Majority Shares, Engineers India Limited (EIL) Enters as One of the Shareholders (Equity Structure OIL: 80.16%, Govt. of Assam: 15.47%, EIL: 4.37%) | 
| October 07, 2021 | MoPNG Approves Revised Refinery Expansion Project Cost of Rs. 28,026 Crore | 
| January 3, 2022 | Share Transfer by OIL to Govt. of Assam Complete (Equity Structure OIL: 69.63%, Govt. of Assam: 26%, EIL: 4.37%) | 
| June 22 & July 04, 2023 | Upgradation of NRL from Schedule-B to Schedule-A - (22.06.2023 Click here) | (04.07.2023 Click here) | 
| August 01, 2024 | Environmental Clearance Obtained for Poly Propylene Unit. - (Click here) |