How to reduce USPTO fees

An inventor can reduce expenses associated with the government filing fees charged by the Patent Office if qualified for a small entity status ($730) or micro-entity status ($400).

Small entity status
An applicant can claim small entity status if:
If the owner is a “person” (i.e. individual or individuals) who has not assigned, granted, conveyed, or licensed, and is under no obligation under contract or law to assign, grant, convey, or license, any rights in the invention.
If the owner is a “small business concern.” Under the SBA regulations, this means that the owner, including affiliates, has fewer than 500 employees and the owner has not assigned, granted, conveyed, or licensed, and is under no obligation under contract or law to assign, grant, convey, or license, any rights in the invention.
A non-profit organization (regardless of size), including institutions of higher education who has not assigned, granted, conveyed, or licensed, and is under no obligation under contract or law to assign, grant, convey, or license, any rights in the invention.
If the owner has transferred or licensed rights, or is under obligation to do so, it can still qualify for small entity status so long as each party individually meets the requirements listed here.

Micro-entity status

Does the applicant qualify as a small entity? (If no, then no micro-entity)
Has the applicant or any joint inventor filed more than four US non-provisional patent applications? (If yes, then no micro-entity, unless those applications were from a prior employment and assigned to the prior employer)
Did the applicant or any listed inventor have an income for the past year that was greater than $150,000? (If yes, then no micro-entity). This number will change annually based upon median US household income.
Have rights in the application been promised or licensed to a non-micro-entity? (If yes, then no micro-entity).