(27)Competent authorities should verify that for the purpose of the advanced IRB Approach, i.e. where own-LGD estimates are used, guarantors are considered eligible where they are rated using a rating system approved under the IRB Approach; other guarantors may also be eligible, provided that they are classified as an institution, a central government or central bank, or a corporate entity that has a credit assessment by an ECAI, and the guarantee meets the requirements set out in Section 3, Chapter 4, Title II in Part Three of Regulation (EU) No 575/2013, which are also applicable for the Standardised Approach.