In the title compound, C(9)H(12)NO(6)P, intra-molecular C-H⋯O hydrogen bonds form five- and six-membered rings. In the crystal, inversion dimers lined by pairs of C-H⋯O hydrogen bonds occur with ring motifs R(2) (2)(10). The O atom of the hydr-oxy group behaves as an accepter and the benzene ring as donor. Adjacent dimers are connected through O-H⋯O links.