You get the premium tax credit by applying for health insurance in your states' marketplace or exchange, or if your state doesn't have a marketplace, healthcare.gov. You will not be able to get premium tax credit if you apply for health insurance directly with a health insurance company.
P.S. I read your question on another page and it included "on a state filing". If this is what you actually asked, Premium Tax Credits in general are given only by the Feds and not the State.