Are there annuities to be paid prior to patent grant but to maintain the patent application in the United States?
CHATGPT says No.
But, https://www.quantifyip.com/blog/article6.aspx says yes.
Not like most countries.
Many countries require annual payments to keep a patent application alive while it is pending and then more annual payments to keep a patent in force. They are called annuities or renewal fees.
The U.S. does have maintenance fees due only after grant. They are due at three points: 3,5, 7.5 and 11.5 years after the date of grant in order to keep a U.S. patent enforceable.