Predicted to enable RNA polymerase II CTD heptapeptide repeat phosphatase activity. Acts upstream of or within negative regulation of G1/S transition of mitotic cell cycle; negative regulation of cell differentiation; and negative regulation of protein phosphorylation. Predicted to be located in nucleoplasm. Is expressed in several structures, including alimentary system; central nervous system; genitourinary system; immune system; and integumental system. Orthologous to human CTDSP1 (CTD small phosphatase 1). [provided by Alliance of Genome Resources, Apr 2022]