We propose a simple theoretical model to take into account the existence of long-term debt regimes, in line with the salient facts observed in the long term. We are particularly interested in the effects of a permanent increase in public debt on long-term growth, and we show that these effects, which are still negative (zero), depend in their size on the debt adjustment variable in the government’s fiscal constraint. Finally, we show that, contrary to the effects on growth, the long-term welfare effects of a permanent increase in public debt can be positive. We conclude that there is an optimal threshold for the general government debt-to-GDP ratio.