This is really confusing because in my country health premiums are paid through your employer and I would've assumed hybe provided health insurance to their employees and artists ..... also surprising that a celeb would be the one to deal with this directly anyway, you'd think they'd have managers of accountants to keep track of payments like this.
In South Korea, it's the same too, except for people who are freelancers or own their own businesses. If you're on monthly salary and hired by your employer as a regular permanent employee with a fixed income, then yes, your taxes and insurance will be deducted before you get your monthly salary. In BTS case, HYBE is technically not their "employer." BTS are not on a $2000 or $3000 monthly salary basis but they're freelancers who are paid per gig and HYBE is like their partner. So people who are freelancers or work part-time jobs or run their own businesses have to report their taxes and pay insurance by themselves.