Mario Rizzo
President of Property Liability at Allstate
Thanks, Tom. Let's start on slide five. Property-Liability earned premium increased 10.7% in the fourth quarter, primarily driven by higher average premiums from rate increases, partially offset by a 2% decline in policies in force. Underwriting income of $1.3 billion in the quarter improved $2.4 billion compared to the prior year quarter due to increased premiums earned, improved underlying loss experience, lower catastrophe losses and operating efficiencies. The chart on the right highlights the components of the 89.5 combined ratio in the quarter, which improved 19.6 points from the prior year quarter. The impact of catastrophe losses and prior year reserve reestimates on the combined ratio, as shown in light blue and gray materially improved compared to the prior year.
Catastrophe losses of $68 million were $711 million or 6.3 points lower than prior year, due to the mild weather conditions experienced in the quarter and favorable loss development from prior period events. Prior year reserve reestimates, excluding catastrophes, were unfavorable and totaled $199 million, representing a 1.6 point adverse combined ratio impact in the quarter and a 0.9 point favorable impact compared to the prior year quarter. Approximately $148 million related to personal auto, driven in part by costs related to claims and litigation and adverse development in National General. The underlying combined ratio of 86.9% improved by 12.3 points compared to the prior year quarter due to higher average premium and the favorable influence of milder weather conditions on accident frequency.
Despite the favorable results in the quarter, the full year combined ratio of 104.5% was significantly impacted by elevated catastrophe losses, primarily from events in the first three quarters, resulting in a catastrophe loss ratio that was four points above the 10-year average from 2013 to 2022. Now let's move to slide six to review Allstate's auto insurance profit trends. The fourth quarter recorded auto insurance combined ratio of 98.9 improved by 1.7 points, compared to the prior year quarter reflecting higher earned premium, lower underlying losses, lower adverse prior year reserve re-estimates and expense efficiencies. The chart shows the underlying combined ratios from 2022 and 2023, and with quarterly reported figures adjusted to reflect the estimated average severity level, as of year-end for each year.
As you can see, the underlying combined ratio decreased each quarter in 2023, reflecting the benefits of the profit improvement plan Tom discussed earlier. As a reminder, we continually reassess claim severity expectations as the year progresses. If the current year expected severity increases or decreases, the year-to-date impact of that change, is recorded in the current quarter, despite a portion of that impact being driven by reassessment of the prior quarters. In 2023, the full year estimate of claims severity decreased in the fourth quarter, so there was a benefit from prior quarters included in reported results in the fourth quarter. When you adjust for this, the reported underlying combined ratio of 96.4% as shown in the table would be 98.2%, as shown in the bar on the graph.
The three preceding quarters all benefit from the adjustment, including Q3, which improved from 10.5% in the presentation shown last quarter to 99.9%, reflecting the latest severity estimate. While loss cost trends remained historically elevated, the rate of increase moderated in the second half of the year, mainly in physical damage coverages. Allstate brand weighted average major covered severity expectations improved from 11% as of the end of the second quarter to 9%, in the third quarter and now the 8% to 9%, at the end of the year. As a reminder, this trend reflects our current best estimate for the year-over-year increase in average severity.
Slide seven shows the impact of our profit improvement actions across the country. As shown on the left, Allstate brand rate increases have exceeded 33% over the last eight quarters, including larger increases in California, New York, New Jersey and Texas, reflective of the elevated loss trends in these states. These four states comprised 36% of Allstate brand auto total written premiums in the US, during 2023. As you know, increases were approved in California, New York and New Jersey in December, so we have yet to see this in our premiums. The chart on the right shows states with an underlying combined ratio of below 100 shown in the light and dark blue bars were 65% of the total in 2023, more than doubling from the percentage at year-end 2022.
Excluding California, New York and New Jersey, the Allstate brand auto insurance underlying combined ratio was 95.9% in 2023. The slide eight shows improving profitability had a negative impact on policies in force during 2023. On the left, you can see that total protection auto policies in force decreased by 2.9%, compared to prior year, as the Allstate brand decline of 6.2% more than offset a 13.3% increase at National General. Allstate brand auto policies in force decreased due to reduced new business volumes and lower retention. National General growth of 581,000 policies in force was mostly driven by nonstandard auto insurance and, to a lesser extent, the rollout of new middle market standard and preferred auto insurance product launches for the Custom 360 product.
The chart on the right shows total personal auto new issued applications for 2023 decreased 6% compared to prior year and the accompanying drivers. Targeted profitability actions within the Allstate brand resulted in a decline in new auto and issued applications of 20% compared to the prior year. The first two red bars reflect the impact of lower new business volume in California, New York and New Jersey -- as well as the direct channel decline in the remainder of the country, which was most directly impacted by the reduction in marketing investment last year. Outside of the three states where profit actions significantly reduced new business Allstate exclusive agents increased production by 6% driven by higher productivity, showing the response of Allstate agents to the changes we've made to incent growth and the opportunity to continue to grow with our agency owners as part of transformative growth.
The acquisition of National General strategically positioned Allstate to grow in the independent agent channel with new business applications, increasing 12% in 2023. National General continues to grow nonstandard auto and generate higher volume from the Custom 360 product launches. Slide nine covers homeowners insurance results, which generated significant profits for the quarter, while full year results were impacted by elevated catastrophe losses in the first three quarters of the year. On the left, you can see net written premium increased 13.3% from the prior year quarter, primarily driven by higher average gross written premium per policy in both the National General and Allstate brands and a 1.1% increase in policies in force.
National General net written premium grew 19.6% compared to the prior year quarter, primarily due to policy in force growth driven by the Custom 360 offering and higher average premiums from implemented rate increases. Allstate brand net written premiums increased 12.5%, driven by average gross written premium per policy increases of 12.2% compared to the prior year quarter and a small increase in policies in force. Allstate agents continue to bundle auto and homeowners insurance at historically high levels. Catastrophe losses of $21 million in the fourth quarter were low by historical standards, reflecting milder weather conditions and favorable development from prior events, contributing to a 62 combined ratio and $1.2 billion of underwriting income for the quarter. Milder weather in the fourth quarter also favorably influenced the underlying combined ratio due to lower noncatastrophe claim frequency.
For the full year, higher catastrophe losses drove the combined ratio increased in 2023 compared to 2022. Full year catastrophe losses of $4.5 billion were higher than our historical experience and translated to a catastrophe loss ratio that was 17 points higher than prior year and roughly 14 points above the 10-year average from 2013 to 2022. As you can see from the chart on the right, the full year underlying combined ratio declined from 70.3% in 2022 to 67.3% in 2023, reflecting higher average premiums from rate increases, partially offset by higher claims severity due to materials and labor costs. With an industry-leading product, advanced pricing, underwriting and analytics broad distribution capabilities and a comprehensive reinsurance program, we will continue to leverage homeowners as a growth opportunity and remain confident in our ability to generate attractive risk-adjusted returns in this line.
Moving to slide 10. Let's discuss how we're advancing transformative growth to provide customers low-cost protection through broad distribution. We remain focused on four key elements of this multiyear initiative, as you can see on this slide. We have improved our cost structure to enhance our competitive price position. In the current environment, with most competitors taking large rate increases, it's difficult to pinpoint competitive position. That said, our relative competitive position likely deteriorated in 2023. But as many of our competitors continue to implement rate increases and our expenses decline, we believe our competitive position will improve, enhancing growth opportunities as part of transformative growth. Redesigned affordable, simple and connected products currently available for auto insurance in seven states with plans for further expansion this year, both improved customer value and deliver a differentiated customer experience.
National General independent agent growth prospects will be further enhanced by expanding Custom 360 products, which were live in 16 states as of year-end 2023, and expect to be in nearly every state by the end of 2024. Expanding customer access will also support market share growth, and we have made good progress in all three channels. Increasing sophistication and customer acquisition continues to advance and will improve the effectiveness of increased advertising spend in 2024 as we look to grow in more states. A new technology ecosystem is also being deployed to improve the customer experience, speed to market and reduce costs for legacy technology platforms.
Let me turn it over to Jess now to talk about expense reductions and other operating results.