After a patent application successfully passes the patent examination process, an issue fee is due (discussed here), then a patent will issue. A patent is normally valid for 20 years from the original filing date, plus any Patent Term Adjustments. In order to have the patent be enforceable for the full term, a series of maintenance fees need to be paid.
I often get asked, when is a Patent Maintenance Fee due?  The first maintenance fee is due 3.5 years after the patent issues (37 C.F.R 120(e)). The second maintenance fee is due 7.5 years after the patent issues (37 C.F.R 120(f)). The third maintenance fee is due 11.5 years after the patent issues (37 C.F.R 120(g)). None of the patent maintenance fees are required. However, if any one of the maintenance fees is not paid, the patent will then go abandoned, and will not be enforceable. If a patent is no longer valuable, the cost of the maintenance fees can be avoided.
Each maintenance fee is progressively higher than the previous. For example, in 2017, for a small entity (an assignee with less than 500 employees), the first maintenance fee is $800.00, the second maintenance fee is $1,800.00, and the third maintenance fee is $3,700.00. A large entity pays twice those amounts. The USPTO micro entity definition qualifies you to pay half those amounts. There is an income limitation and only the first four applications by an inventor qualify for the discounted micro entity fees. This is a lifetime limitation. The America Invents Act (AIA) introduced the discounted micro entity fees.
The United States Patent and Trademark Office (USPTO) started collecting maintenance fees as a way to balance their budget. They have drastically raised these fees over the years.
As registered Patent Attorneys in Michigan and California, we can arrange for the payment of each of these maintenance fees. You can always ask one of our Patent Attorneys for additional information. Please call us at MI - 586-498-0670 or CA - 408-890-6549
If you would like us to analyze your particular situation, call us to set up an appointment to discuss starting an engagement. Please do not send confidential information prior to negotiating an engagement.