Foreign ownership restrictions apply to foreign-licenced persons, and provided there is reciprocity in treatment between Austria and the foreign State: Qualified EU/EEA/Switzerland citizens are entitled to establish in Austria to practice a profession as a chartered accountant subject to equivalence/recognition of professional qualification. Others persons are required to go through the 'full licensing process" (including examination requirements). The majority of the management and external representation of auditing firm must be carried out by persons entitled to exercise the professional license for the relevant professional group independently. Natural persons and companies entitled to practice as chartered accountants can be shareholders in Austrian auditing companies. Natural and legal persons entitled to practice under foreign law can be shareholders up to 25% and provided that there is reciprocity between Austria and the state in which the professional license was obtained and similar training can be proven and the management and representation to the outside are majority carried out by persons entitled to practice in Austria.

"1st chapter
professional law
1. main piece
Fiduciary professions - scope of authorization
accountancy professions
§ 1.(1) Public accountant professions are the following professions:
1. auditor and 2. Tax consultant.
(2) The chartered accountancy professions are liberal professions.
[...]
Public Order – Recognition
§ 5.(1) Public accountant professions may be exercised independently by persons entitled to exercise the profession, i.e. either natural persons or companies.
(2) A natural person is authorized to practice and is therefore entitled to independently exercise a profession as a chartered accountant after being publicly appointed by the Chamber of Chartered Accountants.
(3) A company is authorized to exercise a profession and is therefore entitled to independently exercise a profession as a chartered accountant after it has been recognized by the Chamber of Chartered Accountants.
[...]
branch office
§ 7.(1) Citizens of a member state of the EU or a state party to the Agreement on the European Economic Area or of Switzerland are entitled in accordance with paragraph 2 to settle in the territory of the Republic of Austria to practice a profession as a chartered accountant.
(2) Prerequisites for establishment pursuant to para. 1 are:
1. the nationality of a member state of the EU or a state party to the Agreement on the European Economic Area or Switzerland,
2. the valid authorization to practice a chartered accountancy profession in their home Member State,
3. the existence of the general requirements according to § 8 paragraph 1,
4. the existence of an equivalent professional qualification and
5. the public appointment by the Chamber of Public Accountants.
(3) The following must be attached to the application for a public appointment:
1. a proof of identity,
2. proof of nationality,
3. the proof of professional qualification that entitles you to take up a job as a chartered accountant, and
4. Certificates from the competent authorities of the home Member State of the existence of special trustworthiness, orderly economic circumstances and the absence of serious professional conduct. These certificates must not be older than three months when they are submitted.
[...]
2. main part - Natural people
1st section - General
Requirements
§ 8th.(1) General requirements for the public appointment are: 1. the full ability to act; 2. the special trustworthiness, 3. orderly economic conditions, 4. a valid pecuniary damage liability insurance and 5. a professional seat.
Article 51.General requirements for the recognition of a company that intends to practice the profession of public accountant and activities that are compatible with it are:
1. the existence of a company form according to § 54, 2. a written partnership agreement, 3. a company according to § 55, 4. Partners or shareholders according to § 56,
[...]
Professional seat
§ 12. 
(1) Persons entitled to practice professions are obliged to have a professional seat located in a member state of the EU or a signatory to the Agreement on the European Economic Area.
(2) In the case of a self-employed person entitled to a profession, a professional seat is to be understood as a permanent establishment which, through its personnel, material and functional equipment, ensures that the professional requirements placed on a person entitled to practice are fulfilled.
[...]
Management and external representation
Section 52.(1) Management and external representation must be carried out by persons entitled to exercise their professional authorization independently.
(2) The majority of management and external representation must be carried out by persons entitled to exercise the professional license for the relevant professional group independently, with the company being represented by persons entitled to exercise the professional license for the relevant professional group independently. must be guaranteed individually or collectively without the involvement of others. If there are only two managing directors, it is sufficient if one of them is entitled to exercise the relevant professional authorization independently.
(3) Authorized signatories must be entitled to exercise their professional authorization independently, but can be authorized to represent them externally, regardless of their professional authorization and number.
(4) In the case of auditing firms, the majority of management and external representation must be carried out by persons entitled to exercise the profession who, pursuant to Article 57, are entitled to sign an audit certificate.
(5) If there are only two partners in partnerships or corporations, it is sufficient when exercising the profession of tax consultant and auditor if one of these is a person entitled to practice in the relevant professional group, has a majority interest and is authorized to represent independently. If both the chartered accountant profession of tax consultant and the chartered accountant profession of auditor are exercised at the same time, the partners have equal rights and each have the right to represent independently.
(6) Statutory auditors and auditing firms pursuant to Art. 2 nos. 2 and 3 of the Auditing Directive, which are licensed in another EU Member State or in a signatory state to the EEA or the Swiss Confederation, are entitled to exercise the profession of chartered accountant with regard to company formations Equivalent to the provisions of Section 56.
[...]
Shareholder
Article 56.(1) Shareholders may only be:
1. natural persons entitled to practice, 
2. Spouses, children and registered partners of authorized professionals involved in the company, 
3. Companies that are authorized to practice a chartered accountancy profession, 
4. Private foundations set up by one or more partners in accordance with the Private Foundations Act, Federal Law Gazette No. 694/1993 , the sole purpose of which is to support the persons named in Items 1 and 2 and whose board of directors consists exclusively of persons entitled to exercise the profession,
5. Persons entitled to practice under foreign law if their capital shares in the company assets and their voting rights do not exceed one quarter, provided that there is reciprocity between Austria and the state in which the professional license was obtained and similar training can be proven and the management and representation to the outside are majority carried out by persons entitled to practice in Austria, and
6. For auditing companies, statutory auditors and auditing companies in accordance with Art. 2 Z 2 and 3 of the Auditing Directive that are licensed in another EU member state or a state party to the EEA or the Swiss Confederation, if their capital shares in the company's assets and their voting rights do not exceed three quarters.
(2) Children include all descendants, in-laws, stepchildren and adopted children.
(3) All shareholders are subject to the provisions of this federal law.
(4) Shareholders pursuant to para. 1 no. 2 must have: 1. a main residence located in an EU or EEA member state, 2. the special trustworthiness according to § 9 and  3. Orderly economic circumstances according to § 10.
(5) All shareholders must hold their rights in their own name and on their own account. The fiduciary exercise of company rights, profit-participating loans and similar contractual relationships are not permitted. Silent participations are only permitted by the group of people described in paragraph 1 and must be reported to the Chamber of Public Accountants immediately.
(6) In the case of stock corporations, the shares must be registered. The transfer of registered shares is only permitted with the consent of the company.
[...]
2nd section - Interdisciplinary collaboration
Requirements
Article 59.(1) General requirements for the recognition of a company to which shareholders other than those listed in Section 56 (1) belong and which intend to carry out other activities in addition to exercising a profession as a chartered accountant are:
1. the professional appointment or recognition for the authorized exercise of other permissible professional activities according to § 60, 2. the existence of a company form according to § 61, 3. a written partnership agreement, 4. a company according to § 62, 5. Shareholders according to § 63, 6. a concluded pecuniary damage liability insurance according to § 11 and 7. Orderly economic circumstances according to § 10.
(2) Further requirements for the recognition of a company that intends to carry out other activities in addition to exercising a profession as a chartered accountant are:
1. When exercising the profession of chartered accountant, tax consultant
a) a division of the capital shares or the share capital or share capital and the voting rights and b) a management and a representative,  which guarantees at least equal rights for those entitled to exercise the profession of tax advisor with those of other professions pursuant to Section 60,
2. when practicing the chartered accountancy profession
a) a division of the capital shares or the share capital or share capital and the voting rights and b) a management and a representative, which guarantees at least equal rights for persons entitled to practice who practice the chartered accountancy profession with those of other professions pursuant to Section 60,
3. while simultaneously practicing the chartered accountancy professions of tax consultant and auditor
a) a division of the capital shares or the share capital or share capital and the voting rights, so that persons who have the professional license to act as tax consultants or auditors together have at least 25% of the shares and voting rights, whereby these in turn must have equal rights to each other and b) management and representation by persons entitled to exercise the professional license independently, individually or collectively without the involvement of others.
(3) Representation of the company in matters relating to the scope of authorization of the chartered accountant by members of the professions pursuant to Section 60 (1) is inadmissible if the activity in question is not also covered by the authorization of the respective professional accountant. In all cases of paragraph 1, § 52 paragraph 2 applies accordingly.
[...]
shareholder
Section 63.(1) Only the following persons may be shareholders:
1. natural persons entitled to practice,
2. Companies that are authorized to practice a chartered accountancy profession,
3. natural persons who independently carry out another professional activity in accordance with Section 60 (1),
4. Companies that exercise another professional activity according to § 60 paragraph 1, and
5. persons authorized under foreign law to carry out another professional activity pursuant to Section 60 (1) if their capital share in the company's assets and their voting rights do not exceed one quarter.
(2) Shareholders must have:
1. a main residence located in an EU or EEA member state, 2. the special trustworthiness according to § 9 and 3. Orderly economic circumstances according to § 10.
(3) Article 56, paragraph 5 shall apply to shareholders pursuant to paragraph 1, item 1.
(4) Section 56 (7) applies to all shareholders. Section 56 (8) applies to company shares held by persons entitled to practice law. [...]"(Act on Accounting, Auditing, Tax Advising and Related Professions (BGBl. I Nr. 137/2017), last amended by BGBl. I No. 141/2020, § 12 [google translation])
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"AUSTRIA
*List A, I/A Direct investment:
– In the country concerned by non-residents.
Remark: The reservation applies only to: [...]
ii) auditing;
iii) investment by non-EU residents in accountancy services exceeding 49 per cent; [...]" (OECD Code of Liberalisation of Capital Movements, Annex B)
Act on Accounting, Auditing, Tax Advising and Related Professions (BGBl. I Nr. 137/2017), last amended by BGBl. I No. 141/2020, § 12 [google translation]
OECD Code of Liberalisation of Capital Movements, Annex B
[<a href="https://www.ris.bka.gv.at/GeltendeFassung.wxe?Abfrage=Bundesnormen&Gesetzesnummer=20009983">Act</a>],[<a href="https://www.oecd.org/investment/investment-policy/Code-capital-movements-EN.pdf">Code</a>]