This is a Request for Information (RFI) for market research purposes only, not a solicitation for proposals. The Internal Revenue Service (IRS) seeks to identify qualified sources capable of providing a comprehensive online tax research platform for up to 7 users. The platform must support advanced-level international tax research, including comparative tools for bilateral tax treaties and multilateral instruments, as well as access to national legislation and case law. Responses are due by June 23, 2026, at 10:00 a.m. Eastern Standard Time. No budget amount or performance location is specified.