AARP’s endorsement helped secure passage of President Barack Obama’s health care overhaul. Now the seniors’ lobby is telling its employees their insurance costs will rise partly as a result of the law.

In an e-mail to employees, AARP says health care premiums will increase by 8 percent to 13 percent next year because of rapidly rising medical costs.

And AARP adds that it’s changing copayments and deductibles to avoid a 40 percent tax on high-cost health plans that takes effect in 2018 under the law. Aerospace giant Boeing also has cited the tax in asking its workers to pay more. Shifting costs to employees lowers the value of a health care plan and acts like an escape hatch from the tax.