In PA if you decline Dental care employer offered benefit must you sign a declination form?

If you choose not to take dental coverage offered by your employer must you sign a form declining and does the employer have to have everyone enrolled or not sign one acknowledging it was offered.
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This varies by company. At my company (based in NY), you either get the insurance, or you sign a declination paper and are ineligible to sign up for it again until the next year during a period of time called "Open Enrollment". This is a fairly common practice.
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