Whereas I have failed to find any specific prohibition against using as deduction other than allowed itemizing of expenses or the standard, the nearest is the definition of taxable income ---> 26USC 63
(b)Individuals who do not itemize their deductions In the case of an individual who does not elect to itemize his deductions for the taxable year, for purposes of this subtitle, the term “taxable income” means adjusted gross income, minus—
(2) the deduction for personal exemptions provided in section 151, and
(3)any deduction provided in section 199A.
This clearly says that the default position is "Standard Deduction" unless and until the taxpayer "elects" to use Itemized deduction ( with its own rules as to what is and what is not allowed and how much as deduction ). Thus the taxpayer is faced only with two choices -- ( 1) use Standard Deduction allowed for the tax year and filing status OR (2) Elect to use Itemized Deduction.
I think therefore the answer is NO -- you cannot use a number different than the Standard Deduction , unless you choose to Itemize .
