<p>Is it true that when you want to change the subject of the test you registered to take, you can just do it on the day of the test and not inform collegeboard? What about if I chose two, but decided to take only one? Thanks!</p>
<p>You can replace any test for any test, take more than you registered for, or take fewer than you registered for. Collegeboard will bill you accordingly. You cannot, however, replace a test with a language listening test.</p>