The German site selection process for high-level nuclear waste was initially planned to conclude in 2031, with the deep geological repository sealed around the year 2080. However, in 2022, substantial delays were announced by the responsible federal agency, pushing the site selection to 2046 or even 2068. With this delay come uncertainties regarding the duration, consequential knowledge management, and funding. German nuclear waste management activities are funded by the external segregated fund KENFO, which is designed to ensure sufficient funding via generating returns on investments (ROI) in the coming decades. Given recent developments, we assess the adequacy of the fund volume based on seven scenarios depicting potential process delays. We find that the target ROI of 3.7% will not suffice in any case, even if the site selection concludes in 2031, and that cash injections of up to EUR31.07 billion are necessary today to ensure that the fund volume will suffice. We conclude that cost estimations must be updated, KENFO must increase its target ROIs, potential capital injections must be openly discussed by policymakers, and a procedural acceleration should be implemented to ensure that financial liabilities for nuclear waste management are minimized for future taxpayers.