What is this sentence structure?
I will let you know once (it is paid.)

What is the sentence structure when you say it is paid as in the above sentence?

Thank you.

Question

What is this sentence structure?
I will let you know once (it is paid.)

What is the sentence structure when you say it is paid as in the above sentence?

Thank you.

Answer

"Once"  in this sentence is a conjunction, meaning "as soon as", "on the occasion when".

Answer

I will let you know when it is paid.