There are premium subsidies available in the exchange, but you're not eligible for them if the plan offered by your employer is considered affordable and provides minimum value (this is true for your family members as well, if they have access to your employer-sponsored plan, even if the employer-sponsored plan is only affordable for the employee's portion of the coverage; this is known as the family glitch). Most employer-sponsored plans are affordable and do provide minimum value. So if you're shopping for an individual market plan instead, chances are high that you'll have to pay full price for it, without any subsidies.
But the ACA changed all that. Medical underwriting is no longer used, although applicants can now only enroll during open enrollment or a special enrollment period triggered by a qualifying event (similar to how enrollment works for employer-sponsored plans). Essential health benefits are now covered on all new individual major medical plans in every state. And millions of people are receiving premium subsidies that cover the majority of their premiums for plans purchased in each state’s health insurance exchange (the ACA’s consumer protection reforms apply to plans sold outside the exchanges as well, but the subsidies are only available in the exchange). The ACA also limits the percentage of premiums that insurers can use for administrative costs, including profits and executives’ salaries; insurers have refunded billions of dollars to consumers as a result of the new rules.
For some consumers, buying individual health insurance is the only health coverage option. However, even if you have health insurance from your employer, an individual/family health insurance policy may still be an option to save money. With health insurance premiums increasing every year and employers passing more of the costs onto their employees, your company's health insurance may not be the best deal, especially if you need to cover a family.