Which rider would not increase the premium for a policyowner?

The rider that would not increase the premium for a policyowner is the impairment rider. This rider typically serves as an amendment to a policy, allowing for certain impairments to be included without charging an additional premium. It is helpful in providing coverage even when standard underwriting would categorize the applicant as a higher risk, thereby accommodating individuals with pre-existing conditions.

In contrast, the other riders mentioned usually do result in an increase in premium. For instance, the waiver of premium rider typically allows a policyholder to skip premium payments during times of disability, which can lead to higher premiums due to the additional coverage being offered. The accidental death rider provides an extra benefit in the event of death by accident, which also usually incurs additional costs. The guaranteed insurability rider permits the insured to purchase additional insurance at specific times without needing to show evidence of insurability, a feature that logically results in premium increases due to the added flexibility and security provided by this option. Therefore, the impairment rider is unique in its purpose and its impact on premiums compared to the others listed.