When the Every Student Succeeds Act passed, one of the things that educators were most excited about was the chance to cut down on the number of tests kids have to take, Specifically, the law allows some districts to offer a nationally recognized college-entrance exam instead of the state test for accountability.

But that flexibility could be more complicated than it appears on paper.

Here’s a case in point: Oklahoma, which hasn’t finalized its ESSA application yet, has already gotten pushback from the feds for the way that it had planned to implement the locally selected high school test option in a draft ESSA plan posted on the state department’s website. In that plan, Oklahoma sought to offer its districts a choice of two nationally recognized tests, the ACT or the SAT. Importantly, the state’s draft plan didn’t endorse one test over the other—both were considered equally okay.

The department took a peek at Oklahoma’s draft, which was posted online, and called the Sooner State to tell them, essentially, that they would have to make a choice. The department told Oklahoma its pitch wasn’t compliant with the law, because neither the ACT or SAT was considered the official statewide high school assessment. At the time, Oklahoma told the department it would consider seeking a waiver from ESSA so it could move forward with the two-test system. About a month later, however, the state, which hasn’t yet finalized its ESSA plan, is still mulling its options. So a waiver ask may or may not be in the offing.

If Oklahoma does decide to pursue a waiver from ESSA, it won’t be the first state to ask for flexibility from the brand new law. New Jersey, Kentucky, and Florida are all mulling waivers, including when it comes to testing.

In May, the department said if want to offer a local choice of tests, they must meet a bunch of requirements, some of which may prove to be tough hurdles. For instance, any and all tests on the menu must have made it through the department’s notoriously rigorous peer review process. ACT has partially met the requirements of that review, and the SAT, a newer test, is still working on it.

To be sure, SAT and ACT are already used as the statewide for accountability in more than a dozen states. But the requirements appear to be different, and potentially more challenging, if a state is going to offer a range of choices when it comes to high school tests.