If I have no medical insurance, and I pay the penalty, can I be denied medical care when I need it? My understanding of the aca was to help cover the costs of the uninsured as well as to make insurance more affordable.
If you don't have coverage, and owe the fee, that means that you are either choosing to pay the fee rather than get cost assistance. Or that you have affordable coverage options, but are paying the fee anyway.
In America we don't turn people away in emergencies, but you won't be able to get care outside of an emergency unless you pay out-of-pocket or have a health plan.
Even in an emergency you'll be getting a bill. You can claim bankruptcy and pass your bills on to the taxpayer... but wouldn't seeing what coverage options you have be a better bet?
Check out HealthCare.Gov don't assume your options, fill out an application and find out. You may be surprised by how affordable coverage can be.
ps. To clarify, the ACA helps the uninsured by having better giving consumers more benefits, rights, and protections and making sure coverage is affordable. It doesn't do much to cover those who don't have coverage. That being said, if you are eligible for Medicaid and you show up at a hospital they can help you fill out the application if you are eligible... Of course if you are eligible you don't owe the fee and should just get Medicaid now anyway.