Doing some trainings and requested VAT... what next?

I am employed and working as a software engineer in Zurich...

I have been requested to deliver some online trainings and for this the company (USA) is requesting me my VAT number...

I understood that this is not needed if you perform under 100K CHF... but they seem to have this as mandatory... What should I do on this case? Or is usually done?

Thanks so much for the responses!!

A UID enterprise number would likely be sufficient for the US company. It can be applied for at the SVA Zurich:

https://svazurich.ch/formulare/2000_…/hinweise.html

Are you independent or a regular employee? In the second case you should have filled in your employer as the purchaser