A drawback of the simple SF-TDDFT approach is that it often leads to significant spin contamination in bond-breaking regions of the potential surface. For singlet photochemistry, the practical upshot is that it can be difficult to distinguish singlets from triplets in the photochemically-relevant regions of the surface. Statetracking algorithms (based on wavefunction overlap) are used in practice to overcome this problem, although this feels to us like a stopgap solution. A "spin-adapted" version of the theory (SA-SF-TDDFT) has been reported, which solves this problem in an elegant way by introducing the minimal number of additional determinants necessary to obtain spin-pure Ŝ2 eigenstates, however at present its analytic gradient is not available. This method can be used to spot-check the state assignments of the simple SF-TDDFT approach. Alternatively, a "mixed reference" version of SF-TDDFT has also been developed, which eliminates the spin contamination to a useful degree for low-lying singlet states, even if it does not rigorously afford spin eigenstates.