We quantified permafrost plateau and post-thaw carbon (C) stocks across a peatland permafrost thaw chronosequence in Interior Alaska to evaluate the amount of C loss with thaw. Peat core macrofossil reconstructions revealed three stratigraphic layers of peat: (1) a base layer of fen/marsh peat, (2) forested permafrost plateau peat and, (3) collapse-scar bog peat (at sites where permafrost thaw has occurred). Radiocarbon dating revealed that peat initiated at all sites within the last 2,500 years and that permafrost aggraded during the Little Ice Age (ca. 250 – 575 years ago) and degraded within the last several decades. We found the timing of permafrost thaw within each feature was not related to thaw bog size, as hypothesized. Their rate of expansion may be more influenced by local factors, such as ground ice content and subsurface water inputs. We found C losses due to thaw for the century of approximately 34% of the C available, but the absolute amount of C lost (kg m^-2) was over 50% lower than losses previously described in other Alaskan peatland chronosequences. We hypothesize that the difference stems from the process by which permafrost aggraded, with sites that formed permafrost epigenetically (significantly later than the majority of peat accumulation) experiencing less C loss with thaw than sites that formed syngenetically (simultaneously with peat accumulation). We suggest that C:N ratios can provide a first order estimate of how much peat has been processed prior to permafrost aggradation, helping to predict the magnitude of C loss with thaw.