Net income for the fourth quarter of 2021 included the aftertax amortization of the cost of reinsurance of $15.5 million or $0.08 per diluted common share and a net aftertax investment loss on the company's investment portfolio of $6.8 million or $0.03 per diluted common share.
Net income in the fourth quarter of 2020 included a net aftertax gain from the closed block individual disability reinsurance transaction of $32 million or $0.16 per diluted common share.
A net aftertax reserve increase related to assumption updates of $133.5 million, which is $0.66 per diluted common share; and a net aftertax investment gain on the company's investment portfolio, excluding the net aftertax realized investment gain associated with the closed block individual disability reinsurance transaction of $1.6 million or $0.01 per diluted common share.
So excluding these items, aftertax adjusted operating income in the fourth quarter of 2021 was $182 million or $0.89 per diluted common share compared to $235.3 million or $1.15 per diluted common share in the year ago quarter.
As we turn to our financial results, our fourth quarter played out largely as we anticipated, with aftertax adjusted operating earnings per share at $0.89 for the fourth quarter.
colonial life produced a solid level of income this quarter, with a strong adjusted operating return on equity of approximately 16%.
Premium growth in the fourth quarter on a year-over-year basis was just under 3% for our core businesses in aggregate, with growth of 3% for Unum US, 7% for international businesses and 1% for colonial life.
The age demographics are a key driver for our business and there was a slight decrease to 35% of national deaths in the fourth quarter from 40% in the prior quarter.
And finally, our capital position remains in a very, in very healthy shape, even after paying more than $0.5 billion in life claims through the pandemic.
The weighted average risk-based capital ratio for our traditional U.S.-based life insurance companies was approximately 395% to close the year and holding company cash totaled $1.5 billion.
Both of these metrics are well ahead of our long-term targets and relative to year-end 2020, holding company cash remained stable and RBC improved by approximately 30 points.
In addition, we added $400 million of pre-capitalized trust securities, which gives us contingent capital on top of our pre-existing credit lines.
For the fourth quarter in the Unum US segment, adjusted operating income was $81.4 million compared to $88.5 million in the third quarter.
Within the Unum US segment, the group disability line reported adjusted operating income of $34.1 million in the fourth quarter compared to $39.5 million in the third quarter.
We saw promising trends in premium income, which increased 2.9% relative to the third quarter and 5% on a year-over-year basis, with increasing levels of natural growth as we benefit from improving employment levels along with rising wages.
The expense ratio was elevated this quarter at 29.9% compared to 28.1% in the third quarter, which reflected higher people-related costs and technology spend to support our digital strategies.
The ratio did improve slightly to 78.3% from 78.9% in the third quarter, primarily driven by a lower level of incidence in the short-term disability line.
Adjusted operating income for Unum US group life and AD&D declined to a loss of $71.7 million for the fourth quarter from a loss of $67.1 million in the third quarter.
This impacted the quarter by approximately $15 million.
The benefit ratio improved to 98.3% for the fourth quarter compared to 100.6% in the third quarter.
We were impacted by the continued high level of national COVID-related mortality, which was a reported 94,000 in the third quarter and increased to a reported 127,000 in the fourth quarter.
For our group life block, we estimate that COVID-related excess mortality claims declined from over 1,900 claims in the third quarter to an estimated 1,725 claims in the fourth quarter.
Accordingly, our results reflect an improvement to approximately 1.4% of the reported national figure in the fourth quarter compared to approximately 2% of the reported national figures in the third quarter.
We also experienced a higher average benefit size, which increased to around $65,000 in the fourth quarter from just over $60,000 in the third quarter.
Now, looking at the Unum US supplemental and voluntary lines, adjusted operating income totaled $119 million in the fourth quarter compared to $116.1 million in the third quarter, both of which are very strong quarters that generated adjusted operating returns on equity in the range of 17% to 18%.
The voluntary benefits line reported a strong level of income as well, with a benefit ratio in the fourth quarter declining to 42.9% from 46.6% in the third quarter, primarily reflecting strong performance across the A&H products.
And finally, utilization in the dental and vision line decreased relative to the third quarter leading to an improvement in the benefit ratio to 65.6% compared to 75% in the third quarter.
Now, looking at premium trends and drivers, we were pleased to see an acceleration in premium income growth for Unum US in the fourth quarter, with a year-over-year growth of 3%.
For full year 2021, premium income increased 1%.
The group disability product line had a very positive quarter, with premium increasing 5% year over year, with strong growth in the STD line as well as the benefit of natural growth on the in-force block.
We estimate the benefit we're seeing from natural growth across our businesses to be in the 3% to 3.5% range measured on a year-over-year basis, with different impacts to our various product lines.
To date, we've seen more of a benefit from rising wages overall, with the benefit from higher employment levels being more pronounced in the less than 2,000 lives sector of our blocks than in our larger case business.
For the group life and AD&D line, premium income increased 2.1% year over year, benefiting from higher persistency and favorable trends and natural growth.
Compared to a year ago, fourth quarter sales were lower by 4.7%.
Finally, in the supplemental voluntary lines, premium income increased 0.6% in the fourth quarter relative to last year, with strong sales growth in both the voluntary benefits and the individual disability recently issued lines, a year-over-year increase of 8.3% in dental and vision premium income, as well as strong improvement in persistency in the voluntary benefits line.
We had a very good quarter, with adjusted operating income for the fourth quarter of $27.1 million compared to $27.4 million in the third quarter.
The primary driver of our international segment results is our Unum UK business, which generated adjusted operating income of GBP 18.7 million in the fourth quarter compared to GBP 18.4 million in the third quarter.
The reported benefit ratio for Unum U.K. was 81.4% in the fourth quarter compared to 79.2% in the third quarter.
On a local currency basis to neutralize the impact from changes in exchange rates, Unum UK generated growth of 5.1% with strong persistency, good sales and the continued successful placement of rate increases on our in-force block.
Additionally, sales in Unum UK were strong in the fourth quarter, increasing 28.1% over last year.
Unum Poland generated sales growth of 43.6%, a continuation of the strong growth trend this business has been producing.
They remain at healthy levels and in line with our expectations, with adjusted operating income of $80 million in the fourth quarter and $80.1 million in the third quarter.
One of the primary drivers of results between the third and fourth quarters was an improvement in the benefit ratio in the fourth quarter to 52.5% compared to 55.9% in the third quarter.
We were pleased to see a continuation in the improving trend in premium growth for colonial life, which did increase 1.1% on a year-over-year basis after being flat to negative over the past four quarters.
For the fourth quarter, sales for colonial life increased 7.8% compared to a year ago and for the full year 2021, sales increased 16.1%.
Persistency for colonial life ended the year in a strong position, increasing to 79.3% for the full year compared to 77.8% in 2020.
In the closed block segment, adjusted operating income, excluding the amortization of cost of reinsurance related to the closed block individual disability reinsurance transaction and the items related to the reserve assumption update in the prior quarter, was $76.7 million in the fourth quarter compared to $109.8 million in the third quarter.
For LTC, the move in the interest adjusted loss ratio to 82.2% in the fourth quarter from 74.8% in the third quarter was driven by less favorable terminations and recoveries, partially offset by lower submitted new claims.
For the closed block individual disability line, the move in the interest adjusted loss ratio to 75.4% in the fourth quarter from 58.2% in the third quarter was driven by higher submitted claims.
However, we did experience a reduction of approximately $10 million in total miscellaneous investment income from the third quarter to the fourth quarter, with the reduction driven by a lower level of bond calls.
Looking ahead, I'll reiterate from our messaging in prior calls with you that we estimate quarterly adjusted operating income for this segment will, over time, run within a $45 million to $55 million range, assuming more normal trends for investment income and claim results in the LTC and closed disability lines.
So then wrapping up my commentary on the quarter's financial results, the adjusted operating loss in the corporate segment was $45.1 million in the fourth quarter and $45.4 million in the third quarter, which are both generally in line with our expectations for this segment.
I'd also mention that the tax rate for the fourth quarter of 2021 was lower than we historically reported at 17.3%, with the favorability as compared to the U.S. statutory tax rate, driven primarily by tax exempt income and various credits.
The comparable full year tax rate of 20.2% is consistent with our expectations and in line with the past two years.
For the fourth quarter, we saw a decline of approximately $16 million relative to the third quarter, driven by a significant reduction in bond call activity, which was unusually high in the third quarter, but was still elevated above average levels for us in the fourth quarter.
Our alternative investment portfolio remained very strong, generating income of $39.4 million in the fourth quarter compared to $38.2 million in the third quarter.
insurance companies improved to approximately 395% and holding company cash was $1.5 billion at the end of the year, both well above our targeted levels.
In addition, leverage has again trended lower with equity growth and is now 25.3%.
During the fourth quarter, we successfully added $400 million of contingent capital through pre-capitalized trust securities, with a 4.046% coupon and 20-year tenor, which we view as a cost-effective way to enhance our balance sheet strength and flexibility.
In terms of capital deployment in the fourth quarter, we executed an accelerated share repurchase transaction to buy back $50 million of our shares.
We continue to anticipate repurchasing approximately $200 million of our shares during 2022.
Capital contributions in the Fairwind subsidiary were $165 million for the fourth quarter and totaled $285 million for the full year 2021, which was a decline from $424 million in 2020.
The recognition of the premium deficiency reserve for LTC, which is included in the Fairwind capital contributions, totaled $346 million after tax for full year 2021.
Moving to First Unum, given the better position of the LTC Block in that subsidiary, resulting from higher interest rates and the benefit of rate increase approvals for that block during 2021, we were in a position to release $75 million of the asset adequacy reserve after many years of additions to that reserve.
With this reserve release, we were able to take a $30 million dividend out of First Unum in the quarter, the first in several years.
And with the increase in interest rates and repositioning our investment portfolio, the premium deficiency reserve in that block was reduced by $66 million after tax.
So in closing, I wanted to give you an update on our progress in adopting ASC 944 or long-duration targeted improvements.
Specifically, we plan to provide an update on the impact at the transition date as well as our 2022 outlook with a conference call on February 25.

Summary:
So excluding these items, aftertax adjusted operating income in the fourth quarter of 2021 was $182 million or $0.89 per diluted common share compared to $235.3 million or $1.15 per diluted common share in the year ago quarter.
As we turn to our financial results, our fourth quarter played out largely as we anticipated, with aftertax adjusted operating earnings per share at $0.89 for the fourth quarter.
Premium growth in the fourth quarter on a year-over-year basis was just under 3% for our core businesses in aggregate, with growth of 3% for Unum US, 7% for international businesses and 1% for colonial life.
Specifically, we plan to provide an update on the impact at the transition date as well as our 2022 outlook with a conference call on February 25.