The integral and the differential photoionization cross-sections of formaldehyde are computed in the random phase approximation (RPA) coupled with a K-matrix (KM) based technique. The molecular orbitals in the continuum are projected on suitable L-2 special polynomial Gaussian functions. Ionization channels originating from the valence shell occupied orbitals are considered, both in separated and interacting channel (IC) approaches up to a photon energy of 45 eV. It is found that the channel coupling is important in order to reproduce some features in the absorption and ionization spectra.