The deduction for seniors is not part of the standard deduction. It's a separate deduction on a different form. On your 2025 tax return the standard deduction will be on Form 1040 line 12e. The deduction for seniors will be on Schedule 1-A line 37. The total deductions from Schedule 1-A will be on Form 1040 line 13b, and might include other deductions besides the deduction for seniors.
Since the deduction for seniors is not part of the standard deduction, you get the deduction for seniors whether you take the standard deduction or itemized deductions.
A person is considered to be age 65 on the day before their 65th birthday, so you must turn 65 on or before January 1, 2026. Or, as the IRS forms put it, to qualify for the deduction for seniors on your 2025 tax return you must have been "born before January 2, 1961."
