Importantly, given the higher interest rate environment as well as other portfolio considerations, we increased our reserve ratio for commercial real estate office loans to 10%. Our ratio of nonperforming assets to loans and other real estate was 0.35% at September 30 compared with 0.29% at June 30 and 0.20% a year ago. Our third quarter net charge-off ratio of 0.44% increased 9 basis points from a second quarter level of 0.35% as adjusted, and was higher when compared to a third quarter 2022 level of 0.19%. Our allowance credit losses as of September 30 totaled $7.8 billion or 2.08% of period-end loans. Turning to Slide 15. We continue to take action to improve our capital ratios this quarter, increasing our CET1 ratio to 9.7% as of September 30.
The combination of our debt-to-equity conversion with MUFG, earnings accretion net of distributions and balance sheet optimization actions resulted in a 60 basis point increase from last quarter. Importantly, our CET1 capital ratio is now 270 basis points above our regulatory capital minimum. I will now provide fourth quarter forward-looking guidance on Slide 16. In the fourth quarter, we expect net interest income of between $4.1 billion and $4.2 billion. Total revenue, as adjusted, is estimated to be in the range of $6.8 billion to $6.9 billion, including approximately $65 million of purchase accounting accretion. Total noninterest expense, as adjusted, is expected to be approximately $4.2 billion, inclusive of approximately $115 million of core deposit intangible amortization related to Union Bank acquisition.
On a core basis, we expect full year 2024 expenses to be flat with 2023. Our income tax rate is expected to be approximately 23% on a taxable equivalent basis. We expect merger and integration charges of between $250 million to $300 million in the fourth quarter. I’ll now hand it back to Andy for closing remarks.
Andy Cecere: Thanks, John. Turning to Slide 17. The Federal Reserve notified us on October 16 that they have granted us full relief from Category II commitments made in conjunction with the Union Bank acquisition after considering several factors, including actions to reduce our risk profile, strengthen our capital position and provisions related to Category III rules made after we received approval on the Union Bank acquisition. This important decision now subjects us to the same enhanced capital requirements as all other Category III banks, including a three-year phase-in of AOCI into regulatory capital starting in the third quarter of 2025. As expected, we will continue to carefully balance the need to accrete capital with any potential impact to earnings from further balance sheet optimization activities.
Measures to manage the interest rate sensitivity and duration of our available-for-sale securities will continue. Since before our acquisition of Union Bank, our priority has been and will continue to be the strategic execution of capital-efficient growth opportunities across each of our business lines. As a result of the Fed’s decision, we are now well positioned with our enhanced earnings profile and diversified business mix to increase our capital levels, continue our disciplined lending activities and further strengthen our balance sheet. Let me close by thanking our more than 75,000 employees for their dedication to supporting the needs of our clients, communities and shareholders. We’ll now open up the call to Q&A.
Operator: [Operator Instructions] And we’ll go to Ebrahim Poonawala with Bank of America. Please go ahead.
Ebrahim Poonawala: I guess maybe the first question, just around the Fed decision. In its letter, the Fed said, I guess the bank anticipates taking further actions to reduce risk profile and reduce assets and increase capital. So if you don’t mind talking about just what additional actions we should expect. I think you mentioned that the EPS impact could be neutral from here. But just how should we think about what else the Fed expects from you on the risk mitigation side as we move forward into next year?
