EXHIBIT 23 CONSENT OF INDEPENDENT CERTIFIED PUBLIC ACCOUNTANTS We consent to the incorporation by reference in the following Registration Statement of our report dated June 1, 2000, with respect to the financial statements and schedules of the IndyMac/IndyMac Mortgage Holdings, Inc. 401(k) Plan included in this Annual Report (Form 11-K) for the year ended December 31, 1999: Registration Statement Number Form Description ------------- ---- ----------- 333-36085 S-8 Registration of 401(k) Plan Stock Los Angeles, California June 1, 2000 GRANT THORNTON LLP