IAMGOLD Announces Results of Cote Gold Project Update

Toronto, Ontario - IAMGOLD Corporation (NYSE: IAG) (TSX: IMG) ('IAMGOLD' or the 'Company') announced its updated estimate of costs to complete, project economics and life-of-mine ('LOM') plan for the Cote Gold project ('Cote Gold' or the 'Project') in Ontario, Canada. A NI 43-101 technical report will be filed on SEDAR on or before September 17, 2022. The project update concludes the Cote Gold costs, schedule, execution strategy and risk review ('project review and risk analysis') initiated by the Company earlier this year. All dollar amounts are expressed in United States dollars, unless otherwise indicated.

Highlights of the Cote Gold 2022 Technical Report: After-tax net present value at a 5% discount rate ('NPV5%') of $1,109 million on a 100% basis, and an internal rate of return ('IRR') of 13.5% - at a gold price assumption of $1,700 in 2024 and 2025 and $1,600 thereafter and CAD:USD exchange rate of 1.25 (from May 1, 2022); Estimated remaining project costs to complete construction and bring Cote Gold into production of $1,908 million ($1,335 million attributable to IAMGOLD) including escalation and contingency as of May 1, 2022; Mine life of 18 years with initial production expected in early 2024; Average annual production of 495,000 ounces (320,500 ounces attributable) during the first six years following commercial production, and 365,000 ounces (236,000 ounces attributable) over the LOM; LOM average cash costs of $693 per ounce gold ('/oz Au') sold and all-in sustaining costs ('AISC') of $854/oz Au sold; Cumulative net operating cash flow of $6,086 million and after-tax free cash flow of $2,597 million; Cote Gold LOM plan based on Mineral Reserves of 7.2 million ounces in the Cote deposit; Cote deposit Measured & Indicated Mineral Resource estimate (inclusive of Mineral Reserves) of 10.2 million ounces; Gosselin deposit Measured & Indicated Resource estimate of 3.4 million ounces; and District scale potential with demonstrated exploration upside in one of the world's leading mining jurisdictions.

Maryse Belanger, Chair of the Board and Interim President and CEO, said: 'The completion of the Cote Gold project review, risk analysis and updated mine plan is the culmination of months of in-depth analysis of the project, based on first principles, by the Company's management and project teams, EPCM contractor and technical experts. The project today is over 57% complete and the updated project costs and schedule give us greatly improved visibility towards completion. Cote Gold is a project that is being advanced in an environment with significant headwinds, including COVID-19, inflation and other global events - and their impacts on global supply chains, labour availability, and the associated costs of doing business. We are very proud of our teams as they navigate these challenges to continue to advance the project for the benefit of our partners, stakeholders and our business.

'Cote Gold is transformational for IAMGOLD. Once in production, the Project is projected to offer robust free cash flow generation, averaging 365,000 ounces per year at AISC of $854 per ounce for 18 years, based on the 7.2 million ounces currently estimated in Mineral Reserves. There is also tremendous potential for future expansion, starting with the Gosselin deposit, located immediately adjacent to the Cote pit containing 3.4 million ounces in Indicated Mineral Resource and an additional 1.7 million ounces in Inferred Resources. Gosselin has only been drilled to half the depth of Cote and remains open along strike. We believe that Cote Gold is not just a project, but the start of a district, with minimal historical exploration targeting Cote/Gosselin style intrusion-hosted deposits within our 596 km2 land package.

'Given the importance of Cote Gold to achieve our goal of becoming a leading high-margin gold producer, we are actively pursuing various alternatives to increase liquidity to complete construction and deliver Cote on the updated schedule. We expect to address these near-term challenges to advance Cote and better position IAMGOLD as a more resilient, agile company for the current environment.'

The Cote Gold project is a 70:30 joint venture between IAMGOLD, as the operator, and Sumitomo Metal Mining Co., Ltd. ('SMM'), which collectively has a 92.5% ownership in the project. The Company effectively owns 64.75% of the Cote Gold project, including the Cote and Gosselin deposits, and associated land packages. In accordance with the terms of the joint venture, the updated project costs, schedule and LOM plan is being independently reviewed by SMM.

The updated information will be incorporated in a new technical report titled 'Technical Report on the Cote Gold Project, Ontario, Canada' (the '2022 Technical Report') prepared by representatives of SLR Consulting (Canada) Ltd., Wood Canada Limited and IAMGOLD, each of whom is a 'qualified person' (a 'QP'), in accordance with National Instrument 43-101 - Standards of Disclosure for Mineral Projects ('NI 43-101'). The 2022 Technical Report supersedes the technical report on the Cote Gold project dated November 26, 2021 (the '2021 Technical Report'). The 2022 Technical Report will be filed on SEDAR on or before September 17, 2022 and readers are encouraged to review the 2022 Technical Report in its entirety, including all qualifications, assumptions and exclusions that relate to the details summarized in this news release.

Information relating to the property description and location, land tenure, existing infrastructure, history, geology and mineralization, mineral resources, mineral reserves, mining method, mineral processing, infrastructure, environmental, permitting and social considerations remains materially similar to information provided in respect of these elements in the 2021 Technical Report adjusted, as applicable, to reflect the status of the project as of May 1, 2022. In addition, current information in respect of the mine plan, capital and operating costs estimates and economic analysis is presented in the 2022 Technical Report.

Contact:

Graeme Jennings

Vice President

Investor Relations

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Philip Rabenok

Manager

Investor Relations

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Toll-free: 1 888 464 9999

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Si vous desirez obtenir la version francaise de ce communique, veuillez consulter le www.iamgold.com/French/accueil/default.aspx.

CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING INFORMATION

Statements included in this news release, including any with respect to the Company's future financial or operating performance, and other statements that express management's expectations or estimates of future performance, including statements in respect of the prospects and/or development of the Company's projects, other than statements of historical fact, constitute forward-looking information or forward-looking statements, within the meaning of applicable securities laws (collectively referred to herein as 'forward-looking statements') and such forward-looking statements are based on expectations, estimates and projections as of the date of this news release. Forward-looking statements are provided for the purpose of providing information about management's current expectations and plans relating to the future. Forward-looking statements are generally identifiable by, but are not limited to, the use of the words 'may', 'on track', 'will', 'should', 'continue', 'expect', 'budget', 'forecast', 'anticipate', 'estimate', 'believe', 'intend', 'plan', 'schedule', 'guidance', 'outlook', 'potential', 'seek', 'target', 'strategy', or 'project' or the negative or other variations of these words or comparable terminology. Forward-looking statements contained in this news release include, without limitation, statements with respect to: the Company's guidance for production at Cote Gold, including estimated timing and amounts thereof; total cash costs; all-in sustaining costs; the estimation of mineral reserves and mineral resources; the realization of mineral reserve and mineral resource estimates; the intention of the Company to file the 2022 Technical Report; estimated impairment charges; expected capital expenditures; operations outlook; the progress of development at Cote Gold, including progress of project expenditures and contracting processes; the timing for commencement of commercial production at Cote Gold; the Company's plans and expectations with respect to liquidity management; the future price of gold and other commodities; permitting timelines; exchange rates and currency fluctuations; requirements for additional capital; and the Company's decisions with respect to capital allocation; and the impact of COVID-19, inflation, global supply chain disruptions and the war in Ukraine on the Company, including its operations, the project schedule for Cote Gold, key inputs, staffing and contractors.

The Company cautions the reader that forward-looking statements are necessarily based upon a number of estimates and assumptions that, while considered reasonable by management, are inherently subject to significant business, financial, operational and other risks, uncertainties, contingencies and other factors, including those described below, which could cause actual results, performance or achievements of the Company to be materially different from results, performance or achievements expressed or implied by such forward-looking statements and, as such, undue reliance must not be placed on them. Such risks, uncertainties, contingencies and other factors include, but are not limited to: the Company's business strategies and its ability to execute thereon; risks associated with the process of estimating mineral reserves and mineral resources; the condition and results of the mining industry as a whole, and the gold mining industry in particular; changes in the global prices for gold or other commodities (such as diesel and electricity); the ongoing impact of COVID-19 (and its variants), inflation, global supply chain disruptions and the war in Ukraine on the Company and its workforce, the availability of labour and contractors, key inputs for the Company and global supply chains; government actions taken in response to COVID-19 and other public health emergencies and pandemics, including new variants of COVID-19, and any worsening thereof; legal, litigation, legislative, political, economic or security developments in the jurisdictions in which the Company carries on business; the volatility of the Company's securities; assessment of carrying values for the Company's assets, including the ongoing potential for material impairment and/or write-downs of such assets; title disputes; input in the management of certain of the Company's assets by other companies or joint venture partners; the lack of availability of insurance covering all of the risks associated with the Company's operations and projects; unexpected geological conditions; potential shareholder dilution; potential activist engagements; increasing competition and consolidation in the mining sector; changes in tax laws, including mining tax regimes; the failure to obtain in a timely manner from authorities key permits, authorizations or approvals necessary for exploration, development or operations at the Company's operations; the inability to participate in any gold price increase above the cap in any collar transaction entered into in conjunction with a gold sale prepayment arrangement; the availability of necessary capital and impacts on the Company's liquidity levels; access to capital markets and financing; the Company's level of indebtedness; the Company's ability to satisfy covenants under its credit facilities and other debt instruments; changes in interest rates; adverse changes in the Company's credit rating; the Company's choices in capital allocation; effectiveness of the Company's ongoing cost containment efforts; the ability to execute on the Company's de-risking activities and measures to improve operations; risks related to third-party contractors, including reduced control over aspects of the Company's operations and/or the failure of contractors to perform as expected; risks arising from holding derivative instruments; changes in U.S. dollar and other currency exchange rates, interest rates or gold lease rates; the speculative nature of exploration and development, including the risks of diminishing quantities or grades of reserves; the fact that reserves and resources, expected metallurgical recoveries, capital and operating costs are estimates which may require revision; the presence of unfavourable content in ore deposits, including clay and coarse gold; inaccuracies in life of mine plans; failure to meet operational targets; geotechnical difficulties and major equipment failure; information systems security threats and cybersecurity; laws and regulations governing the protection of the environment; employee relations and labour disputes; the maintenance of tailings storage facilities and the potential for a major spill or failure of the tailings facilities due to uncontrollable events, such as extreme and unpredictable weather or seismic events; physical and regulatory risks related to climate change; attraction and retention of key employees and other qualified personnel; availability and increasing costs associated with mining inputs and labour; the availability of qualified contractors and the ability of contractors to timely complete projects on acceptable terms; the relationship with the communities surrounding the Company's operations and projects; indigenous rights or claims; illegal mining; and the inherent risks involved in the mining industry generally. Please see the Company's AIF or Form 40-F and the 'Risk and Uncertainties' section of the Company's management discussion and analysis as at and for the six months ended June 30, 2022, available on www.sedar.com or www.sec.gov/edgar.shtml for a comprehensive discussion of the risks faced by the Company and which may cause actual results, performance or achievements of the Company to be materially different from results, performance or achievements expressed or implied by forward-looking statements.

Although the Company has attempted to identify important factors that could cause actual results to differ materially from those contained in forward-looking statements, there may be other factors that cause results not to be as anticipated, estimated or intended. There can be no assurance that such statements will prove to be accurate, as actual results and future events could differ materially from those anticipated in such statements.

The Company disclaims any intention or obligation to update or revise any forward-looking statements whether as a result of new information, future events or otherwise except as required by applicable law.

NON-GAAP FINANCIAL MEASURES

This news release contains non-GAAP financial measures, including cash costs per ounce sold ('COC'), AISC per ounce sold, sustaining and expansion capital expenditures, average realized gold price and available liquidity. The Company believes that, in addition to conventional financial measures prepared in accordance with IFRS, certain investors use these non-GAAP financial measures to assess the performance of the Company. These non-GAAP financial measures do not have any standardized meaning prescribed by IFRS, may not be comparable to similar measures presented by other companies and should not be considered in isolation or as a substitute for measures of performance prepared in accordance with IFRS.

Cash costs include mine site operating costs such as mining, processing, administration, royalties, production taxes, and realized derivative gains or losses, exclusive of depreciation, reclamation, capital expenditures and exploration and evaluation costs. AISC include cost of sales exclusive of depreciation expense, sustaining capital expenditures, which are required to maintain existing operations, capitalized exploration, sustaining lease principal payments, environmental rehabilitation accretion and depreciation, by-product credits, and corporate general and administrative costs. These costs are then divided by the Company's attributable gold ounces sold by mine sites in commercial production in the period to arrive at COC and AISC per ounce sold. The Company believes that the use of COC and AISC per ounce sold metrics will assist analysts, investors and other stakeholders of the Company in assessing its operating performance and its ability to generate free cash flow.

The Company presents its sustaining capital expenditures in its all-in sustaining costs to reflect the capital related to producing and selling gold from its mine operations. The distinctions between sustaining and expansion capital used by the Company align with the guidelines set out by the World Gold Council. Expansion capital is capital expenditures incurred at new projects and capital expenditures related to major projects or expansion at existing operations where these projects will materially benefit the operations. This non-GAAP financial measure provides investors with transparency regarding the capital expenditures required to support the ongoing operations at its mines, relative to its total capital expenditures.

CAUTIONARY NOTE TO U.S. INVESTORS REGARDING DISCLOSURE OF MINERAL RESERVE AND MINERAL RESOURCE ESTIMATES

The mineral resource and reserve estimates contained in this news release have been prepared in accordance with NI 43-101 and the Canadian Institute of Mining, Metallurgy and Petroleum ('CIM') - CIM Definition Standards on Mineral Resources and Mineral Reserves, adopted by the CIM Council, as amended (the 'CIM Standards').. These standards are similar to those used by the United States Securities and Exchange Commission (the 'SEC') Industry Guide No. 7, as interpreted by the SEC staff. However, the definitions in NI 43-101 and the CIM Standards differ in certain respects from those under Industry Guide 7. Accordingly, mineral resource and reserve information contained in this news release may not be comparable to similar information disclosed by United States companies. Under the SEC's Industry Guide 7, mineralization may not be classified as a 'reserve' unless the determination has been made that the mineralization could be economically and legally produced or extracted at the time the reserve determination is made.

As a result of the adoption of amendments to the SEC's disclosure rules (the 'SEC Modernization Rules'), which more closely align its disclosure requirements and policies for mining properties with current industry and global regulatory practices and standards, including NI 43-101 and the CIM Standards, and which became effective on February 25, 2019, the SEC now recognizes estimates of 'measured mineral resources', 'indicated mineral resources' and 'inferred mineral resources.' In addition, the SEC has amended definitions of 'proven mineral reserves' and 'probable mineral reserves' in its amended rules, with definitions that are substantially similar to those used in NI 43-101. Issuers must begin to comply with the SEC Modernization Rules in their first fiscal year beginning on or after January 1, 2021, though Canadian issuers that report in the United States using the Multijurisdictional Disclosure System ('MJDS') may still use NI 43-101 rather than the SEC Modernization Rules when using the SEC's MJDS registration statement and annual report forms.

United States investors are cautioned that while the SEC now recognizes 'measured mineral resources', 'indicated mineral resources' and 'inferred mineral resources' under the SEC Modernization Rules, investors should not assume that any part or all of the mineral deposits in these categories will ever be converted into a higher category of mineral resources or into mineral reserves. These terms have a great amount of uncertainty as to their economic and legal feasibility. Under Canadian regulations, estimates of inferred mineral resources may not form the basis of feasibility or pre-feasibility studies, except in limited circumstances.

Investors are cautioned not to assume that any 'measured mineral resources', 'indicated mineral resources', or 'inferred mineral resources' that the Company reports in this news release are or will be economically or legally mineable. Further, 'inferred mineral resources' have a great amount of uncertainty as to their existence and as to their economic and legal feasibility. It cannot be assumed that any part or all of an inferred mineral resource will ever be upgraded to a higher category.

The mineral reserve and mineral resource data set out in this news release are estimates, and no assurance can be given that the anticipated tonnages and grades will be achieved or that the indicated level of recovery will be realized.

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