The primary law governing Saint Kitts and Nevis nationality regulations is the Saint Christopher and Nevis Citizenship Act, which came into force on 28 February 1984.

Saint Kitts and Nevis is a member state of the Organisation of Eastern Caribbean States (OECS). Kittian and Nevisian nationals have automatic and permanent permission to live and work in any other OECS country.

With few exceptions, almost all individuals born in Saint Kitts and Nevis are automatically citizens at birth. Foreign nationals may become citizens by naturalisation after living in the country for at least 14 years and fulfilling a good character requirement. Individuals who make a substantial financial contribution to the state are eligible for a facilitated naturalisation with no required period of residence.

Saint Kitts and Nevis was previously a colony of the British Empire and local residents were British subjects. Although Saint Kitts and Nevis gained independence in 1983 and citizens no longer hold British nationality, they continue to have favoured status when residing in the United Kingdom; as Commonwealth citizens, they are eligible to vote in UK elections and serve in public office there.

Terminology Nationality establishes one's international identity as a member of a sovereign nation. Though it is not synonymous with citizenship, for rights granted under domestic law for domestic purposes, the United Kingdom, and thus the commonwealth, have traditionally used the words interchangeably.

Acquiring Kittitian and Nevisian nationality Kittitians and Nevisians may acquire nationality through adoption, birth, naturalisation, or registration.

By birth Birthright nationality applies to:

Persons born within the territory, except those who are born to persons like foreign diplomats, who have immunity from legal processes, or to foreign parents whose country is at war with the Kittitian and Nevisian sovereign; Persons born abroad to at least one parent, who is Kittitian and Nevisian, or parents who would have acquired such nationality had the parent not died prior to independence; Foundlings; or Persons born aboard a ship or aircraft which is registered in Saint Kitts and Nevis or a ship or aircraft which may be unregistered but owned by the government of Saint Kitts and Nevis.

By registration Nationality by registration includes those who have familial or historic relationship affiliations with Saint Kitts, Nevis, or Anguilla. It also includes a programme to acquire nationality through investment. Persons who can acquire nationality by registration include:

By affiliation Persons who were the wife or widow of a national who acquired nationality at the time of independence, or would have acquired nationality except for the death of the spouse; Post-independence, the spouse of a national; Persons who were born abroad before 1 January 1983, to at least one parent who was a Kittitian and Nevisian national at the time of birth, or to Kittitian and Nevisian parents or grandparents who would have acquired such nationality had they not died prior to independence; Persons who are nationals of a Commonwealth country, who have become residents of Saint Kitts and Nevis and resided in the territory or worked for the government for at least fourteen years; or Minors under the age of majority who are legally adopted by a national at the issuance of an adoption order.

By investment The program for acquiring citizenship through investment in Saint Kitts and Nevis is the oldest such program in the world, having been launched in 1984.

Persons seeking citizenship through investment must meet the following requirements;

The primary applicant must be 18 years of age or older. Applicants must make a minimum investment in either approved real estate; or a donation, known as the Sustainable Island State Contribution (SISC) into the Federal Consolidated Fund; or a donation to an Approved Public Benefactor.St. Kitts And Nevis Government Press Release. (2023, July 27). St Kitts and Nevis announces further monumental changes to its Citizenship by Investment Programme. St. Kitts And Nevis Government. Retrieved July 28, 2023, from https://ciu.gov.kn/wp-content/uploads/2023/07/SKN-Press-Release-SKN-CBI-July_2023_Final.pdf.https://web.archive.org/web/20230728095706/https://ciu.gov.kn/wp-content/uploads/2023/07/SKN-Press-Release-SKN-CBI-July_2023_Final.pdfSt. Kitts and Nevis Government. (2023, July 27). Sustainable Island State Contribution (SISC). Ciu.Gov.Kn. Retrieved July 28, 2023, from https://ciu.gov.kn/investment-options/sustainable-island-state-contribution-sisc/.https://web.archive.org/web/20230728101553/https://ciu.gov.kn/investment-options/sustainable-island-state-contribution-sisc/St. Kitts and Nevis Government. (2023, July). CBI Options. Retrieved July 29, 2023, from https://ciu.gov.kn/investment-options/https://web.archive.org/web/20230729072552/https://ciu.gov.kn/investment-options/ The minimum real estate investment is US$400,000. The minimum donation contribution is US$250,000.00 for a single applicant and US$350,000.00 for a family of four. Applicants must also pay non-refundable application and due diligence fees, provide the required documentation for adequate background, police, and due diligence checks, provide the required financial disclosure information, and complete an interview.

Government-approved agents are responsible for assisting applicants and submitting their applications to the Citizenship by Investment Unit for review. Once an application is successfully approved, applicants must make the specified monetary investment within three months in order to be granted citizenship.

By naturalisation Ordinary naturalisation in Saint Kitts and Nevis can be obtained by adult persons of legal capacity, who in the 12 months prior to submitting an application resided in the territory, are of good character, and intend to be a resident of Saint Kitts and Nevis. Applicants petition the Minister responsible for immigration, who considers whether the applicant has resided within the territory for fourteen years and poses no threat to national security or public order. Upon approval, applicants must take an Oath of Allegiance.

Loss of nationality Nationals may voluntarily renounce their affiliation with Saint Kitts and Nevis, if the declarant is a legal adult and is able to acquire other nationality, eliminating the prospect of statelessness within twelve months. Renunciation may not be accepted if Saint Kitts and Nevis is at war with the proposed new source of nationality, or such renunciation would pose a threat to the nation. Denaturalisation may occur if a person obtained nationality through fraud, false representation, or concealment; if they have committed acts of treason; if they have committed acts of disloyalty or service to a foreign government; if they are found guilty of certain criminal offences; if they lose their nationality in another Commonwealth country; and in the case of nationality by investment for failure to meet requirements of the program.

Dual nationality Dual nationality has been permitted in Saint Kitts and Nevis from independence.

History Spanish and French colonial period (1493–1625) Spain claimed St. Jorge's and San Martín Islands from 1493, but by the sixteenth century the original names given the islands were replaced on Spanish maps as San Cristóbal and Nieves, respectively. Anguilla's date of discovery by Europeans is unknown, but it appeared on a map from 1523. Over the next century, there were a few attempts to settle the islands by the Spanish and French, but no permanent settlements were made. Primarily the islands of the Lesser Antilles were used as waystations to replenish food, water, and wood supplies for Dutch, English, French, and Spanish sailors. In 1620, Ralph Merifield and Thomas Warner secured a Royal Patent from King James VI and I to establish trading centers and proprietary colonies in the islands of Saint Christopher, Nevis, Barbados, and Montserrat. Warner, who had been living in the failed North Colony of The Guianas, and was returning home to England, landed on Saint Kitts, and thought that it had a suitable environment to grow tobacco. In 1624, he arrived on Saint Kitts with less than two dozen settlers to find three French inhabitants living with the native Kalinago people. The following year, a French ship, under the command of Pierre Belain d'Esnambuc, arrived on the island with 80 sailors with the intention of harboring to repair their damaged ship. Alarmed by the arrival of so many Europeans, the Kalinago put up a fight, but were defeated when the English and French joined forces against them. Both Warner and d'Esnambuc returned to their respective homelands and received commissions to establish settlements on the island.

British and French joint period (1625–1713) In Britain, allegiance, in which subjects pledged to support a monarch, was the precursor to the modern concept of nationality. The crown recognized from 1350 that all persons born within the territories of the British Empire were subjects. Those born outside the realm — except children of those serving in an official post abroad, children of the monarch, and children born on a British sailing vessel — were considered by common law to be foreigners. Marriage did not affect the status of a subject of the realm. Similarly, the Ancien Régime of France developed a system of feudal allegiance in which subjects were bound together by a scheme of protection and service tied to land ownership. Possession of land was typically tied to military and court service and omitted women because they could not perform those obligations. Thus, French nationality also derived from place of birth in French territory, until the nineteenth century, but under feudal law married women were subjugated to the authority of their husbands under coverture.

Warner returned to Saint Kitts in 1625 with 100 new British colonists and in 1627, d'Esnambuc returned with several hundred French settlers. Within five days of his arrival, he and Warner drew up a pact to divide the island. The French settled in the coastal regions and the English occupied the center of the island, calling their colonies St. Christophe and Saint Christopher (Saint Kitts), respectively. In 1628, Anthony Hilton, a colonist on Saint Kitts, established a settlement on Nevis, which attracted interest from others settled on Saint Kitts, who began migrating to the nearby island. Sugar was introduced to the islands in 1640 and by 1650 had become the main staple crop. Along with sugar's introduction, importation of slaves increased and a plantation society developed. In 1650, another contingent of settlers from Saint Kitts ventured to Anguilla to colonize it and in 1660, a sole governor was assigned for Saint Kitts and Anguilla, when proprietary rule ended and the colonies were taken over by the crown. The Second Anglo-Dutch War resulted in the British expulsion from the islands in 1666, but at the war's conclusion in 1667, terms of the Treaty of Breda returned all colonies to their former owners. By the 1670s, the French colony of St. Christophe numbered 3,600 settlers with 4,500 slaves compared to the British colony of Saint Kitts, which had less than 1,000 settlers with around 900 slaves. The French crown took control of St. Christophe colony in 1674, when the proprietors went bankrupt. By 1680, St. Christophe had only 130 planters left, whereas the population of Saint Kitts included 3,000 colonists and 4,300 slaves, Nevis had 3,500 colonists with 5,000 slaves, and Anguilla had 500 inhabitants with no slaves.