Tax reform and lower catastrophe losses helped make all the difference for private U.S. property/casualty insurers in the 2018 first quarter.

Their net income after taxes surpassed $17 billion during the first three months of the year, more than double the $7.9 billion produced in Q1 2017, according to data compiled by ISO (a Verisk business) and the Property Casualty Insurers Association of America.

Robert Gordon, PCI’s senior vice president for Policy, Research and International, said tax reform was a significant driver of the positive results.

“The results were likely impacted by market shifts that are rippling through the industry caused by last December’s federal tax reform,” Gordon said in prepared remarks.

ISO/PCI said that net premiums were affected by a number of insurers changing their use of offshore reinsurance, and keeping more premiums within the United States.

In a word of caution, Gordon pointed out that the industry surplus actually fell by $3.2 billion from the end of last year, though that was due to higher than usual dividend payments to shareholders, plus major dips in unrealized capital gains in insurers’ portfolios.

ISO President Neil Spector said in prepared remarks that the results were also driven, in part, by “significantly lower” catastrophe losses. He argued that greater reserve releases due to lower cost of prior years’ claims also helped, as well as the growing economy and rising net premiums that come with that trend.

Here’s a rundown of other U.S. P/C insurer results from Q1:

• Loss and loss-adjustment expenses from catastrophes dropped to $5 billion in Q1 2018, from $7.7 billion in Q1 2017.
• Favorable reserve development was $7.4 billion, versus $5.5 billion over the same period a year ago.
• Overall, insurers produced net underwriting results that came in at a positive $4.2 billion in the 2018 first quarter, compared to seven quarters in a row of underwriting losses.
• Insurer net written premiums grew 15.7 percent to $156.6 billion compared to $135.4 billion and a 4 percent increase in Q1 2018.
• Earned premium growth accelerated to 9.4 percent, from 3.5 percent a year ago.

Sources: ISO/Versisk, PCI