A practicing Filipino accountant filad his 1st. 2nd and 3rd quarter ' a points income tax for 2021 claiming optional standard deductions. In the course of the remaining taxable yea r. he realized that he has enough documents to substantiate his business expenses. He plans to use use itemized deduction for his annual income tax return for 2021 to minimize his taxable income. Will this be allowed by the BIR? Why or why not?