According to the Companies Act, a company must have at least two directors and one of the two directors or, where there are more than two directors, at least two of them shall be ordinarily resident in Brunei Darussalam. A prior minimum stay of 183 in Brunei Darussalam is required for one person to qualify as resident for the purposes of the law. For the purposes of the OECD FDIRRI,due to the prior residency requirement, it is assumed that such a restriction constitutes a barrier for nominating foreigners as directors; hence it is scored as a nationality requirement for at least one member of the board of directors.
"ANNEX I - SCHEDULE OF BRUNEI DARUSSALAM
Sector: All
Obligations Concerned: National Treatment (Article 9.4), Senior Management and Boards of Directors (Article 9.11)
Measures: Companies Act (Chapter 39), Business Names Act (Chapter 92), Miscellaneous Licences Act (Chapter 127), Co-operative Societies Act (Chapter 84), 
Employment Agencies Order 2004, Administrative Measures and Guidelines
[...] 
Description: Investment […]
3. Company Directorship:  A foreign national may not sit on the board of directors of an enterprise established in Brunei Darussalam unless one of the two directors or, where there are more than two directors, at least two of them shall be ordinarily resident in Brunei Darussalam. For the purposes of this entry, a foreign national shall apply to the Ministry of Finance in order to be considered as being “ordinarily resident in Brunei Darussalam” (ANNEX I - SCHEDULE OF BRUNEI DARUSSALAM, Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP))
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"Interpretation 2. (1) In this Act —[...]
“director” includes any person occupying the position of director of a corporation by whatever name called and includes a person in accordance with whose directions or instructions the directors of a corporation are accustomed to act and an alternate or substitute director;[...]
“resident in Brunei Darussalam” has the same meaning as in section 2 of the Income Tax Act (Chapter 35);
[...]
DIRECTORS AND MANAGERS
Number of directors
138. (1) Every company registered after 1st January 1957, being the date of commencement of this Act, shall have at least two directors. (2) One of the two directors or, where there are more than two directors, at least two of them shall be ordinarily resident in Brunei Darussalam. [...]" (COMPANIES ACT, 1956 [Cap 39], as amended)
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"Interpretation. 
2. In this Act, unless the subject or context otherwise requires — [...]
“resident in Brunei Darussalam”— (a) in relation to an individual, means a person who, in the year preceding the year of assessment, resides in Brunei Darussalam except for such temporary absences therefrom as to the Collector may consider reasonable and not inconsistent with a claim by such person to be resident in Brunei Darussalam, and includes a person who is physically present or who exercises an employment (other than as a director of a company) in Brunei Darussalam for 183 days or more during the year preceding the year of assessment; (b) in relation to a company or a body of persons, means a company or a body of persons the control and management of whose business is exercised in Brunei Darussalam; [...]" (Income Tax Act (Chapter 35), as amended)
ANNEX I - SCHEDULE OF BRUNEI DARUSSALAM, Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP)
COMPANIES ACT, 1956 [Cap 39], as amended
Income Tax Act (Chapter 35), as amended
[<a href="https://www.mfat.govt.nz/assets/Trade-agreements/TPP/Annexes-ENGLISH/Annex-I.-Brunei.pdf">CPTPP</a>],[<a href="https://www.agc.gov.bn/AGC%20Images/LAWS/ACT_PDF/cap39bb.pdf">Act</a>],[<a href="https://www.agc.gov.bn/AGC%20Images/LAWS/ACT_PDF/cap035.pdf">Act</a>]