Page 16-16-17 of 418.1.0 SUMMARY 1.1 Executive Summary SLR Consulting (Canada) Ltd (SLR) and Wood Canada Limited (Wood) were retained by IAMGOLD Corporation (IAMGOLD) to prepare a Technical Report on IAMGOLD’s Ct Gold Project (the Project or the Property) which is located approximately 125 km southwest of Timmins in northern Ontario, Canada. The Project hosts both the Ct Gold deposit (Ct deposit or Ct) and Gosselin deposit (or Gosselin). In 2019, SLR acquired Roscoe Postle Associates Inc. (RPA), which had been involved with the Ct Gold Project since 2011. For the purpose of the Technical Report, references to SLR include RPA. The purpose of this Technical Report is to support the disclosure of Mineral Resources and Mineral Reserves as of June 30, 2021, and to provide an update on the advancement of the Project. This Technical Report conforms to National Instrument 43-101 Standards of Disclosure for Mineral Projects (NI 43-101) as published by the Canadian Securities Administrators. The effective date of this Technical Report is October 18, 2021. Independent Qualified Persons from SLR and Wood visited the Ct Gold property frequently from 2018 to present, most recently on July 19 to 21, 2021 (SLR) and May 7 to 9, 2019 (Wood). IAMGOLD is a mid-tier Canadian gold mining company operating in three regions globally: North America, South America, and West Africa. Within these regions IAMGOLD is developing potential mining districts that encompass operating mines and construction, development, and exploration projects. IAMGOLD’s operating mines include Essakane in Burkina Faso, Rosebel (including Saramacca) in Suriname and Westwood in Canada. A solid base of strategic assets is complemented by the Ct Gold Project in Canada, the Boto Gold development project in Senegal, as well as greenfield and brownfield exploration projects in various countries located in the Americas and West Africa. IAMGOLD acquired the Project in 2012 following its acquisition of Trelawney Mining and Exploration Inc. (Trelawney or TME). Trelawney had carried out exploration activities on the Property since 2009. The Project, which is currently under construction, is a 70:30 joint venture between IAMGOLD, as the operator, and Sumitomo Metal Mining Co., Ltd. (Sumitomo). Anticipated to begin operation in Q3 2023, the Project will feature open pit mining at rates up to 62 million tonnes per annum (Mtpa), and processing of 13 Mtpa of ore via high pressure grinding rolls (HPGRs), gravity concentration, whole-ore leaching, and gold recovery from solution using carbon-in-pulp (CIP). Production is forecast to average 489,000 oz per annum for the first five years of an 18 year mine life. In addition to the Ct deposit, this Technical Report describes an initial Mineral Resource estimate for nearby Gosselin, which represents potential for additional mine life for the Project. Units of measurement used in this Technical Report conform to the metric system. All currency in this Technical Report is US dollars (US$) unless otherwise noted. 1.1.1 Conclusions The Project is well advanced, with construction underway, and detailed engineering at 82% completion. Risks to Mineral Resource and Mineral Reserve estimates, or to projected economic outcomes, are low in comparison to advanced properties undergoing engineering studies. IAMGOLD Corporation | Ct Gold Project, SLR Project No: 233.3498.R0000 NI 43-101 Technical Report - November 26, 2021 1-2 Due to the substantial capital expenditures involved in mine development projects, developments are prone to cost overruns versus budget. Construction costs can be impacted by a wide variety of factors, certain of which are beyond the control of IAMGOLD. The significant capital expenditures and long time period required to develop new mines or other projects are considerable and changes in costs and market conditions or unplanned events or construction schedules can affect project economics. The Project may experience further increases in capital expenditures. In addition, construction and permitting delays could result in a prolonged schedule and increased project costs, and delay impacting mining activity or commissioning of the mill plant, which ultimately could impact the timing of production. To mitigate some of these risks, operational and economic reviews are in place, with a focus on project budget, future cash flows, profitability, and results of operations. Further conclusions by area are as follows. 1.1.1.1 Geology and Mineral Resources • Ct Measured and Indicated Resources total 365.5 million tonnes (Mt) at an average grade of 0.87 g/t Au, containing 10.20 million ounces (Moz) Au. An additional 189.6 Mt at an average grade of 0.63 g/t Au, containing 3.82 Moz Au are estimated in the Inferred Mineral Resource category. The Mineral Resources are estimated at a 0.3 g/t Au cut-off grade, based on a gold price of US$1,500/oz Au, and have an effective date of December 19, 2019. • Gosselin Indicated Resources total 124.5 Mt at an average grade of 0.84 g/t Au, containing 3.35 Moz Au. An additional 72.9 Mt at an average grade of 0.73 g/t Au, containing 1.71 Moz Au are estimated in the Inferred Mineral Resource category. The Mineral Resources are estimated at a 0.3 g/t Au cut-off grade, based on a price of US$1,500/oz Au, and have an effective date of October 4, 2021. • There is excellent exploration potential to increase the Mineral Resources at Gosselin. o Gosselin Mineral Resources are not yet included in the current Life of Mine (LOM) plan for the Project and represent potential for future mine life extensions. 1.1.1.2 Mining and Mineral Reserves • Proven and Probable Mineral Reserves are estimated to total 233.0 Mt at an average grade of 0.96 g/t Au, containing 7.19 Moz. Mineral Reserves are estimated at a 0.35 g/t Au cut-off grade, based on a price of US$1,200/oz Au, and have an effective date of October 1, 2021. • Pit optimization parameters, pit slope design, financial assumptions, pit-shell selection, and mining dilution and recovery factors remain unchanged from 2018. 1.1.1.3 Metallurgical Test Work • Metallurgical test work completed since 2009 has included: comminution (Bond low-impact (crusher), rod mill (Rwi) and ball mill work (Bwi) indices, Bond abrasion indices (Ai), semiautogenous grinding (SAG) mill comminution (SMC), HPGR, piston press, and Atwal) tests, gravity recoverable gold (GRG) tests, cyanide leaching (effect of head grade, effect of grind size, reagent usage, CIP modelling, cyanide destruction, solid–liquid separation and barren solution analysis) test work, development of recovery projections; and review of the potential for deleterious elements. IAMGOLD Corporation | Ct Gold Project, SLR Project No: 233.3498.R0000 NI 43-101 Technical Report - November 26, 2021 1-3 • The comminution test work indicated that the material tested was very competent, and that the mineralization is well suited to an HPGR circuit. • The mineralization is free-milling (non-refractory). A portion of the gold liberates during grinding and is amenable to gravity concentration and the response to gravity and leaching is relatively consistent across head grades. Therefore, the lower grade gold material is expected to exhibit the same level of metal extraction. Individual lithologies follow the general trends for grind size sensitivity and cyanide consumption, however, there is evidence of differences in free gold content. Silver content is consistently reported below 2 g/t Ag and the test work does not report on silver recovery. • Overall gold recovery is estimated at 91.8% for the processing of 36,000 tonnes per day (tpd) using the proposed flowsheet. • Cyanide and lime consumption are quite low in comparison to what is typically observed in industry, however, this reflects the lack of cyanicides and other cyanide consumers. Lime consumption is also positively impacted by the basic nature of the ore. • Metal dissolution during cyanide leaching was found to be low, and there are no obvious concerns with deleterious elements. • Overall, metallurgical test results indicate that all the variability samples were readily amenable to gravity concentration and cyanide leaching. Samples selected for metallurgical testing were representative of the various types and styles of mineralization within the different zones. Samples were selected from a range of locations within the deposit zones. Sufficient samples were taken so that tests were performed using adequate sample weights. • For Gosselin a preliminary test work program was complete in the summer of 2020. The comminution parameters and gold recovery of Gosselin material are similar to those of the Ct ore. Cyanide and lime consumption were slightly higher for Gosselin material, due to the higher copper and sulphur content. 1.1.1.4 Mineral Processing • The processing plant is designed for a 36,000 tpd throughput. • Gold recovery is estimated at 91.8%. • Preliminary test work indicates that Gosselin will produce metallurgical results similar to Ct. • The process design uses conventional technology and equipment. The process circuits will include primary crushing, secondary crushing, HPGR, ball milling, vertical milling, gravity concentration and cyanide leaching, followed by gold recovery by CIP, stripping and electrowinning (EW). • Tailings handling will incorporate cyanide destruction and tailings thickening. • The equipment proposed is appropriate for the type of flowsheet. • Reagent usage and storage requirements are typical of the industry and require no specialized handling. • Processing plant throughput will be 36,000 tpd and it is expected that a ramp-up period of 10 months will be required to reach the design throughput. • The processing plant is expected to take 10 months to reach the design throughput of 36,000 tpd. Reliable modelling, a focus on engineering design, and equipment selection will be key to achieving full production in the projected timeframe. IAMGOLD Corporation | Ct Gold Project, SLR Project No: 233.3498.R0000 NI 43-101 Technical Report - November 26, 2021 1-4 1.1.1.5 Environment • Environmental Assessment (EA) processe