Proceeding pursuant to CPLR article 78 (transferred to this court by order of the Supreme Court at Special Term, entered in Albany County) to review a determination of the State Tax Commission which sustained the imposition of an unincorporated business tax. During 1966, 1967 and 1968, the substantial portion of petitioner’s income was derived from commissions he received as trustee of about 15 trusts involving four families. He filed New York State resident income tax returns for those years, but did not file unincorporated business tax returns. Following a hearing, the State Tax Commission concluded that petitioner’s activities in managing the trusts constituted the carrying on of an unincorporated business subject to the unincorporated business tax. Petitioner in earlier years had practiced law as a partner of the law firm of White & Case, and later as a partner of the investment banking firm of Dominick & Dominick until he retired in 1962. The trusteeships which he took on had their origin in personal relationships which he developed while associated with these firms, but he was retained as trustee after he retired. However, one trust was created after he retired. During 1966, 1967 and 1968, petitioner maintained a one-room office on the 30th floor of 14 Wall Street, New York, New York, where he employed a secretary (who had been with him at White & Case and Dominick & Dominick) to, according to petitioner, keep his personal and tax records and attend to his personal correspondence. Petitioner reported his trustee commissions partly in Schedule B and partly in Schedule C of his Federal income tax returns. According to Schedule B, his trustee commissions amounted to $159,903.30 in 1966; $178,885.40 in 1967; and $208,627.13 in 1968. On Schedule C, he stated that his "business location” was 14 Wall Street, and he took business deductions for trust and entertainment expenses, for rent on his Wall Street office and for the salary of his secretary. Petitioner made decisions as trustee or cotrustee after receiving investment advice from over 20 banks, brokers and investment firms in at least , seven countries. In all cases the securities were held in custodian accounts in New York and abroad, and petitioner’s decisions as trustee were made wherever he happened to be. The Tax Law imposes a tax upon the income of an unincorporated business (Tax Law, § 701, subd [a]), which is defined as "any trade, business or occupation” conducted by, among others, fiduciaries (Tax Law, § 703, subd [a]). Subdivision (b) of section 703 provides that the "performance of services by * * * a fiduciary, shall not be deemed an unincorporated business, unless such services constitute part of a business carried on by such individual.” At the outset, we reject petitioner’s reliance upon the first paragraph of 20 NYCRR 203.10 (d), which was promulgated pursuant to subdivision (b) of section 703 of the Tax Law. The first paragraph of that regulation merely addresses itself to the question of whether services performed by a fiduciary in furtherance of other business activities of the fiduciary are subject to the unincorporated business tax. The issue before us is not whether the activities of petitioner in managing the trusts were in furtherance of his other business activities, but rather whether the activities themselves constitute a "trade, business or occupation” (Tax Law, § 703, subd [a]; 20 NYCRR 203.1, 203.2). In our view, the record considered as a whole contains substantial evidence to support the determination of the Tax Commission that petitioner through his trustee activities was engaged in the conduct of an unincorporated business. The second paragraph of 20 NYCRR 203.10 provides that "Where an individual *975maintains an office or employs assistants * * * as [a] fiduciary * * * the services so performed will be deemed part of a business regularly carried on if the individual regularly performs or offers to perform similar services to the general public on an individual basis.” The record discloses that after petitioner’s retirement in 1962, he became trustee of one trust. We thus find unpersuasive his contention that he was not holding himself out for business as trustee (20 NYCRR 203.10 [d]), and conclude that because of the trust acquired after his retirement,. the Tax Commission could rationally find that he was holding himself out for business. Petitioner maintains that his Wall Street office was not used to perform any trust functions but that it was only used to attend to his personal correspondence and tax returns. However, the fact that petitioner’s decisions as trustee were made wherever he happened to be, and, in 1966, he spent 144 days in New York, 117 days in 1967, and 135 days in 1968, provided a rational basis to conclude that petitioner in fact utilized the office to conduct the affairs of the trusts. Next, based upon the number of trusts and the sheer size of petitioner’s trustee commissions, his activities as trustee must have been continuous, frequent and regular, as distinguished from casual or isolated, and demonstrate that a substantial amount of time, thought and energy were devoted to his trust activities (see 20 NYCRR 203.1 [a]). Indeed, petitioner obtained investment advice for trust investment purposes from numerous banks, brokers and investment firms in several countries. Furthermore, on Schedule C of his Federal tax returns, entitled "Profit (or Loss) From Business or Profession”, petitioner took considerable "business deductions” including the rent he paid on "business property”, i.e., the Wall Street office, travel and entertainment expenses and the salary he paid his secretary. Judicial review of Tax Commission’s determinations is limited and a determination of the Tax Commission will not be annulled unless shown to be erroneous, arbitrary or capricious (Matter of Grace v New York State Tax Comm., 37 NY2d 193, 195-196). If there are any facts or reasonable inferences from the facts to sustain the State Tax Commission’s determination, it must be confirmed (Matter of Liberman v Gallman, 41 NY2d 774, 777; Matter of Tripp v State Tax Comm., 53 AD2d 763, 764). It is settled that we may not substitute our judgment for the Tax Commission’s "where reasonable minds may differ as to the probative force of the evidence” (Matter of Liberman v Gallman, supra, p 779). In the case at bar, the facts and reasonable inferences therefrom provide a rational basis to sustain the Tax Commission’s determination and it, therefore, must be confirmed. Lastly, we note that all of petitioner’s income attributable to the activities in issue must be allocated to New York State since he did not have a regular place of business outside of New York (Tax Law, § 707, subd [a]). That petitioner had available for his use an office located abroad merely for- purposes of "personal correspondence” does not entitle him to allocate the income. (See, e.g., Matter of Giordano v State Tax Comm., 52 AD2d 691.) Determination confirmed, and petition dismissed, without costs. Mahoney, P. J., Greenblott and Herlihy, JJ., concur.