July 18 (Reuters) - U.S. insurers are requesting the

biggest premium increases for Obamacare plans since 2018,

according to an analysis by health-research firm KFF, prompted

by the looming expiry of premium tax credits and potential

tariffs on medical goods.

Insurers are proposing a median premium increase of 15% for

2026, KFF said, citing data from rate filings of 105 insurers

across 19 states. In recent years, premiums in the plans have

been relatively flat or grown only modestly.

The industry has been struggling with changing enrollment

patterns and rising medical costs. Insurers such as UnitedHealth ( UNH )

and Centene ( CNC ) have suspended their annual earnings

forecasts while others have lowered their profit targets.

Insurance companies pointed to the slower market growth and

a rise in higher-risk patients enrolled in plans under

Affordable Care Act, or Obamacare. The plans primarily serve

people who do not get insurance either through an employer,

Medicaid for low-income people or Medicare for older adults.

The companies also cited the planned 2026 expiration of

COVID-era premium tax credits as a reason, with KFF's analysis

showing insurers will raise premiums by an additional 4% than

they would if the enhanced tax credits were renewed.

For 2026, insurers generally reported that the underlying

cost of healthcare remains around last year's 8% increase.

Several noted that GLP-1 weight-loss and diabetes drugs are

driving costs higher, along with labor market pressures

affecting negotiations with healthcare providers.

Insurers also flagged uncertainty surrounding the "ACA

Integrity Rule", a set of regulations finalized to strengthen

verification and reduce improper enrollments in Obamacare plans,

according to the report.

Health insurers Centene ( CNC ), Molina, UnitedHealth ( UNH ), Cigna,

Elevance, CVS Health, Oscar Health and Kaiser Permanente did not

immediately respond to requests for comment.