Most companies will offer several interest strategies on an annuity, and those can be dependent upon market fluctuations, or contractual stipulations. They can change daily. Other annuities will have set interest rates that may change monthly, or may remain the same. Rates will vary from company to company, and from annuity to annuity within the company. Your best bet is to contact the agent for the company you are interested in, and ask for the current rates. Anything that I’d tell you here would most likely change before you read it.
Deferred annuities normally have a guaranteed interest rate identified in the contract. That is the lowest rate of interest that the company will pay. However, to remain competitive with other investments the company will frequently credit interest on a current rate. That rate is normally higher and is adjusted periodically. Sometimes that rate is applied only to “new money.”