Huqúqu'lláh (Arabic: ﺣﻘﻮﻕ ﺍﻟﻠﻪ, "Right of God"), sometimes called the Law of Huqúq is a socio-economic and spiritual law of the Kitáb-i-Aqdas, a charter document of the Bahá'í Faith, written by Bahá'u'lláh. In its most basic form, it states that Bahá'ís should make a 19% voluntary payment on any wealth in excess of what is necessary to live comfortably, after the remittance of any outstanding debt, to the Universal House of Justice, the chief governing body and administration of the Baha'i faith. The money is then disbursed to social and economic development projects, or similar philanthropic purposes.
Bahá'u'lláh wrote down the law of Huqúqu'lláh in the Kitáb-i-Aqdas in 1873, but he did not accept any payments initially. In 1878 he appointed the first trustee of the Huqúqu'lláh, who had the responsibility of receiving the Huqúq from the Bahá'ís in Iran. Later this was expanded to the Bahá'ís the Middle East. In 1985 information about the Huqúq was distributed worldwide and in 1992 the law was made universally applicable. As the number of payments increased, deputies and representatives to receive the payments have been appointed. In 1991 the central office of Huqúqu'lláh was established at the Bahá'í World Centre in Haifa, Israel. In 2005 the International Board of Trustees of Ḥuqúqu’lláh was formed "to guide and supervise the work of Regional and National Boards of Trustees of Ḥuqúqu’lláh throughout the world." 
During the lifetime of Bahá’u’lláh, the offerings were made directly to him, and following his death, to `Abdu'l-Bahá. In his Will and Testament, `Abdu'l-Bahá provided that Huqúqu'lláh be offered after him “through the Guardian of the Cause of God”. Though now without a Guardian, it is offered through the Universal House of Justice as the Head of the Faith.
- Hájí Sháh-Muhammad Manshádi, Amínu’l-Bayán (’trustee of the Bayán’; d. 1881)
- Hájí Amín (Abdu’l-Hasan Ardikání), Amín-i-Iláhi (‘trustee of God’; 1881-1928)
- Hájí Ghulám-Ridá, Amín-i-Amín (‘trustee of the trustee’; 1928–38)
- Valíyu'lláh Varqá (1938–55)
- `Alí-Muhammad Varqá (1955-2007)
Huqúqu'lláh is said to enable the individual to “purify one’s riches and earthly possessions,” insuring the collection of sufficient funds “that the general Treasury is strengthened,” which makes it possible “to promote the interests of the Cause throughout the Bahá’í world,” and eventually provide for “the relief of the poor, the disabled, the needy, and the orphans,” and other philanthropical purposes.
The offering of Huqúqu'lláh is a spiritual obligation, the fulfillment of which has been left to the conscience of each Bahá’í. Moreover, Huqúqu'lláh is only to be accepted if it is given with "utmost joy, radiance and good pleasure". While the community may be reminded of the requirements of the law of Huqúqu'lláh, it is a principle that no Bahá’í may be appealed to nor solicited to pay it. This offering is to be considered separate from giving to the various Bahá’í funds and takes precedence over them.
The payment of Huqúqu'lláh is based on the calculation of the value of the individual’s possessions, which includes one’s merchandise, property and income, after all necessary expenses have been paid. If a person has possessions or wealth in excess of what is necessary, equal in value to at least nineteen mithqáls of gold (19 mithqáls equal to 2.2246 ounces, currently roughly US$3,000), it is a spiritual obligation to pay nineteen percent of the total amount, once only, as Huqúqu'lláh. Thereafter, whenever an individual acquires more possessions or wealth from income by the amount of at least nineteen mithqáls of gold, one is to pay nineteen percent of this increase, and so on for each further increase.
Certain categories of possessions are exempt from the payment of the Huqúqu'lláh, such as one’s residence, necessary household furnishings, business or professional equipment and furnishings, and others. Bahá'u'lláh has left it to the individual to decide which items are considered necessary and which are not. Specific provisions are outlined to cover cases of financial loss, the failure of investments to yield a profit and for the payment of the Huqúqu'lláh in the event of the person’s death.
- Smith, Peter (2000). "Huqúqu'lláh". A concise encyclopedia of the Bahá'í Faith. Oxford: Oneworld Publications. pp. 189–190. ISBN 1-85168-184-1.
- Compilation on Huqúqu'lláh (2007), quotation 102.
- Smith, Peter (2000). "Covenant". A concise encyclopedia of the Bahá'í Faith. Oxford: Oneworld Publications. pp. 114–5. ISBN 1-85168-184-1.
- Bahá'u'lláh (1873). The Kitáb-i-Aqdas: The Most Holy Book. Wilmette, Illinois, USA: Bahá'í Publishing Trust. ISBN 0-85398-999-0.
- Compilations (1991). Research Department of the Universal House of Justice, ed. Huqúqu'lláh - A Compilation, published in: Compilation of Compilations, Volume I. Bahá’í World Centre: Bahá’í Publications Australia. pp. 489–527.
- Research Department of the Universal House of Justice (April 2007). Huqúqu’lláh - The Right of God. Baha'i Publications Canada and Palabra Publications. ISBN 088867130X.
- Research Department of the Universal House of Justice. (March 1987, revised April 2002). Development of the Institution of Huqúqu’lláh.
- Kitáb-i-Aqdas Project: Decisions, guidance and advice from the Universal House of Justice
- Sixteen Questions about Huququ'llah - by the Universal House of Justice (1991)
- Examples of Huququ'llah Transactions - by the Universal House of Justice (1991)
- Redistribution of Wealth - a compilation by the Baha'i World Centre
- Huqúqu'lláh - Text of a talk given by the Trustee of Huququ'llah, Dr. Ali-Muhammad Varqa (1997)