Leaf litter leaching is a primary function of decomposition that results in key inputs of dissolved organic carbon (C) and nitrogen (N) to freshwater streams over time. It is commonly conceptualized that most leaf leaching occurs within the first 24-72 hours upon submersion. However, increasing evidence suggests that lignin-based leaching can persist much longer in some soil environments. Here, we reconceptualize the freshwater leaf decomposition timeline by investigating late-stage leaching occurring throughout, and up to, four weeks of in-stream conditioning. We decomposed maple (Acer) and oak leaves (Quercus) in a temperate stream and harvested litter at 7, 14, and 28 days. At each harvest date a subset of leaves was leached for an additional 24-hours in the lab. We analyzed mass loss due to decomposition and leaching, changes in leaf C:N ratios due to decomposition and leaching, and leachate dissolved organic C and total dissolved N concentrations. Leaf decomposition rates were calculated from mass loss and ash-free dry mass data. Across harvest dates and for both species leaf mass loss increased by up to an additional 10% following the 24-hour leaching. Our study suggests there is quantitatively significant mass loss and fluxes of leachate-derived dissolved organic carbon and nitrogen due to leaching that results from leaf conditioning throughout the decomposition process. This pathway of mass loss and C and N production has been previously unaccounted for in commonly accepted leaf decomposition conceptual models. Inputs of organic carbon and nitrogen from prolonged leaf leaching (i.e., > 24 hours) likely impacts how elements are cycled and exchanged within aquatic biogeochemical cycles which directly influences freshwater food web dynamics and metabolism.