We consider the Zariski closure of Thom–Boardman strata $\Sigma^{i, j}$ in the jet space for map-germs $(\mathbf{C}^n, 0)\to(\mathbf{C}^p, 0)$. We apply the geometric technique of calculating syzygies to the desingularization of $\Sigma^{i, j}$ constructed by Ronga. We investigate when the normalization of the coordinate ring of $\Sigma^{i, j}$ is rational in the cases $i = n - p + 1$ or $i = j = 1$. We also consider when these coordinate rings are normal with rational singularities.