Is the ne explétif obligatory with avant que ?

Question

For an exercise, I wrote : avant que vous soyez fatigué

But it got marked as incorrect, the correct answer shown has a 'ne'.

I asked some french learners + Gemini AI and they all said that this isn’t required even in written French.

Could someone help me clarify this?

Céline Pickard · Accepted Answer

Bonjour Minh Duc,
When writing French, it is important to include the ne explétif with "avant que". Like Fulya explained, it is definitely optional in speech. Take a look at Cécile's answer here:
I thought that the "ne" was not necessary even in written text. I thought that the Acadamie Française changed it.
I hope this is helpful.
Bonne journée !

Fulya Ozata · Answer

Ne explétif is optional after avant que. In normal modern French, especially in speech, the version without ne is the common one.