Learn French: Nous n'acceptons pas ce tarif, à moins que l'entreprise ne fasse une réduction. - We do not accept this rate, unless the company gives a discount.

The conjunction à moins que (unless) expresses a condition or restriction that hasn't happened yet, so it always requires the subjunctive mood. fasse is the subjunctive form of faire (to do/make).

What is the ne doing before fasse? Does it make the sentence negative?

No, it is not a negative! This is called the 'ne explétif'. It is an optional, untranslatable word often used after certain conjunctions like à moins que or avant que in slightly formal French. The sentence simply means 'unless the company gives a discount.'

Why use the verb faire for 'gives' a discount?

In French, the standard expression is to 'make' a discount (faire une réduction) rather than 'give' one. You might also see accorder une réduction (to grant a discount) in formal business settings.

Can I use prix instead of tarif here?

Yes, prix (price) works perfectly well. However, tarif is very common in business contexts to refer to a set rate, fare, or fee for a service, whereas prix is the broader general word for price.