You can change your test from the SAT to SAT Subject Tests or from SAT Subject Tests to the SAT if you pay the change fee.
There is no charge for changing from one Subject Test to a different Subject Test. If you want to substitute one Subject Test for another, you should do so at the test center. You may substitute any Subject Test offered except the Language Tests with Listening. You cannot change to a listening test on test day because test centers do not have extra CDs. If you want to change to a listening test or from one listening test to another, you must do so by the late registration deadline, or three weeks before the test date if testing internationally.
补充说明一下：
可以先报名SAT Subject考试，然后再更改科目。如果你从SAT Reasoning改成SAT Subject或者反之，需要手续费。如果更改Subject科目，不需要手续费。但你不可以更改language Subject with listening（带听力的），也不可替换。如果你非要更改或替换带听力的考试，那要在报名截止之前或者考前三周更改。
