Presolicitation notice from the Treasury Department of the Internal Revenue Service (IRS) is seeking a contractor for the Modernized E-File (MeF) project. MeF is a mission-critical and mature application that requires a large and highly skilled staff to support its complex and dynamic nature. The contractor must be able to handle a high level of change and meet strict deadlines. MeF is a large-scale complex system that provides electronic filing and payment options for various types of tax returns. It processes hundreds of transactions per second during peak filing periods and employs a diverse group of complex COTS products. The contractor will play a critical role in providing 24/7 coverage for the production environment throughout the filing season and must possess strong knowledge of the tax return processing flow and MeF interfaces. The project aims to provide an internet-based e-Filing platform for all IRS tax returns and extensions. MeF has been in production since 2004 and processes tens of millions of small and large returns each year.