You don't know about these subsidies because you live in Texas. The Supreme Court ruled that states could refuse expanding Medicaid to cover the working poor because the law required states to contribute a fraction of the costs. Currently, a Texan who makes over $5,000 a year is ineligible for Medicaid.
Rick Perry turned down over $79 BILLION of federal dollars from the federal government to raise that limit. The limit for states accepting the Medicaid expansion can provide Medicaid to any individual at 138% the Federal Poverty Level, which is currently $15,856.
Just so that's perfectly clear, if you live in New York and make less than $15,856 you get Medicaid. If you live in Texas you need to earn less then $5,000.
Medicaid expansion and the insurance exchanges are the two foundations of the ACA. Increase the limit for the poor to put them under the umbrella of Medicaid. Create the exchanges to provide affordable access to the lower middle class and self-insured. Texas refused to expand Medicaid and refused to create an exchange. The result is that Texans can only sign up for exchange controlled insurance through the federal exchange (read: not tailored for Texans) AND their poor cannot get expanded coverage at all.
This is a classic example of cutting off your nose to spite your face. Republicans so badly wanted the ACA to fail that they have sacrificed the working poor in their own states.