Here, we derive, implement and assess spinflip time-dependent density-functional based tight binding (SF-TDDFTB) as a cost-effective method to explore the potential energy surface of several photoisomerising molecules. In the next section, we succinitly present the main methodology behind spin-polarized long-range corrected DFTB and we present the formulation of SF-TDDFTB. In the results and discussion, we assess SF-TDDFTB to all-electron SF-TDDFT and MRSF-TDDFT for typical photoisomerising chromophores like the retinal protonated Schiff base, an oxidonole photoswitch, the green fluorescent protein chromophore and the phototrexate photodrug.