AFAIK, that's not a thing for everyone in PA. I wasn't eligible to be put on my husband's insurance before we got married, we lived together and I didn't have a job that offered it. It's for spouses and children only.

The good news is the family glitch loophole should be done away with in 2023. It used to be what was considered legally "affordable" was if your spouse's employer offered spousal insurance and the percentage of your income that was paid to insurance was under a certain number - if it was affordable for employee then it was considered affordable for the whole family. For example, my husband paid like $100/mo for his own insurance, but to add me it would be an additional $400+ (and it's not any cheaper if I went through the regular marketplace). That's not actually affordable for us, but legally it was defined as so. Thank the universe, bc I would have had to make the choice to go without health insurance.

Here is a link to read more about the end of the family glitch loophole and how more people can qualify for reduced insurance premiums now.

ETA - "The family loophole glitch was not an accident – basing affordability on the whole family’s premiums would have increased federal costs significantly."

The government is an unlubed dildo.