Can I write true false in IELTS reading in yes no question instead of yes no?

If you use abbreviations like "T" for True, "Y" for Yes, and so on, your answers will be marked incorrect. To ensure your answers are accepted, always write them in full, avoid spelling mistakes, and make sure your writing is legible.

I know of a student who scored 7 or higher in Listening, Speaking, and Writing, but only 5.5 in Reading because they wrote "T," "F," and "NG" on the answer sheet. As a result, they had to retake the test, wasting time, money, and effort.