Light and elevated temperature induced degradation (LeTID) affects significantly the performance of multicrystalline silicon (mc-Si) solar cells. Even though the underlying mechanisms of LeTID and subsequent regeneration are still unknown, LeTID formation is known to be influenced by surface passivation, firing, and lowtemperature annealing after firing. Since both the firing peak temperature and the cooling profile strongly influence LeTID, firing is presumed to dominate over any preceding low-temperature steps. However, lifetime measurements during illumination (1.0 ±0.1 suns) at 150°C show a clear difference in the LeTID defect density in samples annealed at 200-500°C before aluminum oxide deposition and before firing. Additionally, LeTID becomes worse when the prefiring annealing is performed in an H plasma atmosphere. Therefore, the firing step does not erase the impact of lowtemperature annealing or pre-firing hydrogenation on LeTID. Finally, thinner samples are shown to cause lower initial effective lifetimes (eff) and less LeTID.