The annuity payment is also known as a “patent renewal payment”. Carrying out these payments enables the patent holder to keep their patents in force in the respective jurisdictions.
Although patent laws can differ from country to country, in most jurisdictions, the renewal fee is to be paid annually for a period of 20 years. However, in other jurisdictions, it is only every third to fourth year. The most widespread example of this is the USA, where a patent holder has to renew their patents every 4 years. An extension of the 20 years can occur, see Supplementary protection certificate.