Atty. Matapang is a partner in a general professional partnership. The partnership computes its gross revenues, claims deductions using the optional standard deduction, and distributes the net income to the partners, including Atty. Matapang, in accordance with its articles of partnership. In filing his own income tax return, Atty. Matapang claimed deductions that the partnership already claimed, such as the purchase of law books, entertainment expenses, car insurance, and car depreciation. The BIR disallowed the deductions. Is the BIR correct? Why or why not?