Redesignates existing subparagraph (D) as (E) and inserts a new subparagraph (D) establishing an alternative minimum primary insurance amount for individuals with more than 10 years of work; sets the alternative minimum as an applicable percentage of an annual dollar amount (with 2026 set to the 2025 poverty guideline and later years adjusted), defines 'year of work' as a year with 4 quarters of coverage, and makes the new floor effective for individuals who become eligible after 2025.

Amends 42 U.S.C. 409(k)(1) by inserting additional text (text of the insertion is not provided in the section excerpt).

Adds a new subparagraph defining the term 'Consumer Price Index' to mean the Consumer Price Index for Elderly Consumers (CPI–E, as published by the Bureau of Labor Statistics, Department of Labor).

Amends 26 U.S.C. 1411 by replacing the tax rate specified in subsection (a) with 16.2 percent; modifying provisions in subsection (c)(1)(A); inserting a denial of deduction for net operating losses into subsection (c)(1)(B); striking paragraphs (2), (3), and (4) of subsection (c) and redesignating paragraphs (5) and (6) as paragraphs (2) and (3); and revising the special rule in the redesignated subsection (c)(3) to exclude items subject to the self-employment tax under section 1401 and wages subject to the employment tax under section 3101 from net investment income.

Replaces paragraph (1) of section 1402(b) to provide a new formula for computing the portion of net earnings from self-employment that is subject to the tax imposed by section 1401(a) when the Social Security contribution and benefit base is less than $250,000.

Revises paragraph (1) of 26 U.S.C. 3121(a) to limit the exclusion for payroll-tax purposes to remuneration that exceeds the Social Security contribution and benefit base but does not exceed $250,000 when the contribution and benefit base is less than $250,000; and adds a new subsection (aa) establishing special rules for successor employers treating predecessor-paid remuneration as paid by the successor for purposes of subsection (a)(1).

Modifies clause (i) of 26 U.S.C. 3231(e)(2)(A) to limit the exclusion for railroad retirement taxation to amounts that exceed the applicable base but do not exceed $250,000 in calendar years when the applicable base is less than $250,000.

Amends paragraph (1) and related paragraphs of section 202(d) of the Social Security Act to revise termination and eligibility rules for children's insurance benefits, expand the definition of full-time student to include postsecondary educational institutions described in HEA section 102, permit limited periods of nonattendance, and adjust age-related termination rules.

Modifies clause (iii) of paragraph (1) and paragraph (4) of section 2(d) of the Railroad Retirement Act of 1974 to align student-status and age thresholds with the amended Social Security Act definitions and standards (referencing section 202(d)(7)(E) of the Social Security Act).

Amends section 5(c)(7) of the Railroad Retirement Act of 1974 to replace references to 'full-time elementary or secondary school student' with 'full-time student at an educational institution' consistent with the Social Security Act amendment.