We have developed a numerical model of tidal marsh accretion and channel network development that couples physical sediment processes with vegetation productivity. We have previously demonstrated that under a constant rate of sea level rise, the marsh platform and channel network asymptotically approach a steady state, in which accretion rates everywhere equal the rate of sea level rise and water depth remains constant. In this contribution we focus on new model experiments involving continuously varying rates of sea level rise.We find that there is a significant lag between rates of sea level rise and accretion. Reducing the period of sea level rate oscillations significantly reduces the amplitude of corresponding accretion rate oscillations. Because of the reduced amplitude of accretion fluctuations and the lag relative to sea level rise rates, we question the paradigm that marshes have been in equilibrium with the rate of sea level rise during the Holocene. © 2006 Taylor & Francis Group.