The MP2c correlation, and hence the MP2 energies, are more sensitive to the basis set size and slower to converge than HF, with e.g. MP2 deviations of about 0.7-0.8 kcal/mol for the T zeta bases. This is because the MP2c energy is more prone to the BSIE which is noticeably exacerbated for the smaller cc-pVDZ and cc-pVTZ bases once CP-corrections are ap- plied. Overall, D zeta basis sets do not provide a satisfactory level of convergence, with deviations that might surpass the order of 2 kcal/mol whatever the augmentation or the BSSE correction. At small D and T cardinalities, the best match with PWs is observed when considering only half of the CP correction with the (aug-)cc-pVDZ or cc-pVTZ bases, respectively (Table ), which confirms that the accuracy at such levels is mainly due to a fortuitous cancellation of the BSSE, which lowers the energies, and the BSIE which increases them. Although not formally recommended, this can be exploited for a crude first estimate in case of limited computational budget, as provided for example by the cc-pVTZ/half-CP combination (with potential ∼1 kcal/mol error). For the same reason, the match between non-augmented Q/5 bases and PWs is better with only half-CP correction. For the augmented bases, however, the same conclusions as for HF hold: the MP2c and MP2 energies are generally too low without a full BSSE correction, and approach the CBS PW values from above when corrected. Thanks to this, the overall best agreement between GTOs and PWs is measured for the aug-cc-pV5Z basis with CP correction, that shows a MAE of only 0.06 kcal/mol.