The Accelerating Reliable Capacity Act of 2026 seeks to increase cost certainty for capital-intensive advanced nuclear energy projects that receive loan guarantees through the Department of Energy's Loan Programs Office. It establishes the Accelerating Reliable Capacity Program Account to manage financial risks associated with project cost overruns. Under this program, a "qualifying project" must meet stringent requirements, including submitting a detailed project delivery plan, a Class 2 cost estimate, and a resource-loaded integrated project schedule, all subject to Secretary approval. Enhanced project oversight, including quarterly reviews with stakeholders, is also mandated. For qualifying projects, borrowers are responsible for cost overruns up to 120 percent of the initial point base estimate. Beyond this threshold, the Director of the Loan Programs Office will make payments to the Federal Financing Bank to cover additional overruns, up to a maximum of 30 percent of the point base estimate or $1.2 billion, whichever is less, provided the loan is not in default. The bill also offers enhanced financing terms , allowing loan guarantees to cover up to 200 percent of the project's point base estimate. It requires the Director to seek commitments from the Federal Financing Bank to amend or restructure loans to reflect these overrun payments. Furthermore, the legislation establishes an Accelerating Reliable Capacity Working Group to advise the Secretary on technical, financial, and programmatic aspects of the program. It also expands exceptions to the denial of double benefit provision for certain projects, including those partnering with federal power marketing administrations, military installations, National Laboratories, or using specific nuclear fuel.