A single parent filing as head of household has a simple financial situation with no other deductions or credits apart from the standard deduction. Their financial details for the tax year 2023 are shown. W-2 income: $55,000 Taxable interest (1099-INT): $500 Federal income tax withheld: $5,500 Standard deduction for 2023: $19,400 What amount should the taxpayer enter on line 15 (taxable income) on the 1040 form?