thumb|300px|As Counsellors of State, [[Charles, Prince of Wales, and Prince William, Duke of Cambridge, opened Parliament in May 2022 on behalf of Queen Elizabeth II.]]
Counsellors of State are senior members of the British royal family to whom the monarch can delegate royal functions through letters patent under the Great Seal, to prevent delay or difficulty in the dispatch of public business in the case of their illness (except total incapacity) or of their intended or actual absence from the United Kingdom.
Counsellors of state may carry out "such of the royal functions as may be specified in the Letters Patent". However, by law, counsellors of state cannot grant ranks, titles or peerages.
Royal functions are to be exercised jointly by the counsellors of state or by such number of them as is specified in the letters patent under the Great Seal and subject to any other conditions within. However, there is a legal presumption that counsellors of state should act jointly, and consequently at least two are needed to act, with the absence of one possibly risking a legal challenge.
Counsellors of state are always the monarch's spouse and the first four people in the line of succession who meet the following specifications: they must be British subjects of full age (21 years, or 18 years for the heir apparent or presumptive) who are domiciled in the United Kingdom and not disqualified from becoming monarch. During a regency, the next four eligible people in the line of succession after the regent (and the regent's spouse) may be counsellors. A monarch may also request that Parliament add specific people to their counsellors of state. This was done by Queen Elizabeth II leading to section 3 of the Regency Act 1953 and by King Charles III leading to the Counsellors of State Act 2022.
Queen Elizabeth the Queen Mother lost her eligibility to be a counsellor of state in 1952 upon the death of her husband, King George VI, until section 3 of the Regency Act 1953 restored her position. The provision was specific to her, rather than applying to dowagers generally.
In September 2022, The Daily Telegraph reported that King Charles III wanted the law to be amended to allow only working members of the royal family to serve as counsellors of state. This would take away the eligibility of family members who did not carry out official functions, while creating a possibility for spouses to senior ranking members and those with a lower position in the line of succession to be called upon and fulfil the role.
Questions were raised in the House of Lords in October 2022 by Lord Stansgate about the "suitability" of the Duke of York and Duke of Sussex being counsellors of state when the former had "left public life" and the latter had "left the country". It was subsequently reported that, instead of removing them from the list of counsellors of state, it was being proposed that the pool of counsellors be expanded in order to create a more flexible list of available royals to stand in for the King if needed. On 14 November 2022, the King sent a message to both Houses of Parliament, formally asking for a change in the law that would allow Princess Anne and Prince Edward to be added to the list of counsellors of state. The next day, a bill to that end was introduced in Parliament and it received royal assent on 6 December, coming into force on 7 December as the Counsellors of State Act 2022.
List of current counsellors of state
, those eligible to be appointed counsellors of state to King Charles III are:
{| class="wikitable" style="clear:right; text-align:center"
! Counsellor
! Since
! Relation to Monarch
! Succession order
! Change
|-
| 60px<br/>Queen Camilla
| 8 September 2022
| Spouse
| N/A
| Accession to the throne of Charles III
|-
| 60px<br/>William, Prince of Wales
| 21 June 2003
|
| 1
| rowspan=3|Reached the age of 21
|-
| 60px<br/>Prince Harry, Duke of Sussex
|
| Son
| 5
|-
| 60px<br/>
| 19 February 1981
| Brother
| 8
|-
|-
| 60px<br/>Princess Beatrice
| 8 September 2022
| Niece
| 9
|
|-
| 60px<br/>Prince Edward, Duke of Edinburgh
| rowspan=2|7 December 2022
| Brother
| 15
| rowspan=2|Counsellors of State Act 2022
|-
| 60px<br/>Anne, Princess Royal
| Sister
| 18
|}
Of these seven, Andrew, Prince Harry, and Princess Beatrice do not perform royal duties. If Prince Harry ceases to be domiciled in the United Kingdom, he will become ineligible to be a counsellor of state. In practice, only members of the royal family that perform public duties on behalf of the monarch would be appointed as counsellors of state, thus eliminating the possibility of Harry, Andrew or Beatrice serving in this role.