Relatively small set of provisions — many defended or shaped by powerful industry and wealth-management lobbying — deliver outsized tax breaks to the very rich.

The biggest examples are the preferential tax treatment of capital gains (including carried interest), the “step-up in basis” at death, like-kind (Section 1031) exchanges, certain estate-planning trusts (GRATs and related grantor-trust techniques), and deferrals/competitive rules for multinational profits.

Together these provisions cost the Treasury tens—often hundreds—of billions of dollars a year (and many hundreds of billions over a decade), and they persist in large part because well-funded interests lobby hard to protect them. Below I explain the mechanics, the approximate revenue loss, and the lobbying forces that keep these rules on the books.

1) Preferential capital-gains taxation and carried interest

What it is. Long-term capital gains and qualified dividends are taxed at lower top rates than ordinary wage income. Private-equity and hedge-fund managers often pay capital-gains treatment on what is economically compensation (so-called carried interest).
Revenue cost. The preferential capital-gains structure is one of the single largest “tax expenditures” — Joint Committee on Taxation (JCT) counted roughly $225 billion (JCT basis) in 2024 as the tax-preference on capital gains and dividends. Treating carried interest as ordinary income has been estimated to raise on the order of $12–$14 billion over ten years in various official estimates (CBO/JCT/Treasury analyses differ by method). 
Who defends it. Private equity, hedge funds, asset managers and financial trade groups spend heavily to protect favorable treatment. They make large campaign contributions, hire top K-Street firms, and fund messaging that frames the breaks as necessary for investment and jobs. OpenSecrets and investigative reporting document sustained private-equity activity in Washington. 

2) Step-up in basis at death (the “angel of death” loophole)

What it is. When an owner dies, many assets receive a stepped-up cost basis equal to market value at death — so gains that accrued during the decedent’s life are never taxed unless realized earlier. That allows wealthy families to pass on large unrealized gains tax-free.
Revenue cost. Estimates vary by method: the JCT and Treasury estimate the exclusion-of-gains-at-death line item as costing tens of billions per year (JCT showed ~$60 billion in 2024 on a cash basis; other Treasury and policy estimates projecting longer windows have produced ranges from roughly $100 billion to several hundred billion over a decade, depending on baseline assumptions). One commonly cited Treasury-based figure is roughly $510 billion of foregone revenue across a 10-year window under some assumptions — but smaller JCT estimates also appear depending on the baseline used. The point: this provision is one of the largest giveaways to large, asset-rich estates. 
Who defends it. Wealth-management firms, estate-planning attorneys, and families with significant real-estate and stock portfolios lobby and donate heavily to oppose repeal or narrowing of step-up rules.

3) Like-kind exchanges (IRC §1031)

What it is. Section 1031 allows owners of real estate (and formerly many types of property) to defer tax on gains by swapping into “like” property; the tax is deferred until a later sale.
Revenue cost. JCT and academic summaries put the deferral’s cost in the billions per year. For example, estimates have shown several billion annually (JCT cited about $9.9 billion in one year and larger multi-year totals; five-year and ten-year sums in JCT/analyses reach into the tens of billions depending on the window). 
Who defends it. The real-estate industry (NAR, commercial real-estate groups, exchange facilitators) has a powerful, well-coordinated lobbying effort that emphasizes job creation, liquidity and property markets — and it has repeatedly blocked or diluted repeal efforts. 

4) Estate-planning trusts and grantor-trust techniques (GRATs, IDGTs, etc.)

What it is. Wealthy families use devices like short-term GRATs, intentionally defective grantor trusts and dynasty-trust structures to shift future appreciation out of taxable estates while keeping control.
Revenue cost. Estimates depend on the reform proposed. The Treasury and Greenbook analyses have shown single-digit-to-low-double-digit billions over 10 years for many targeted GRAT reforms (Greenbook and JCT historical estimates provide ranges; TaxLawCenter and CRS summarize available scores). Reform advocates argue closing common GRAT abuses could raise several to many billions. 
Who defends it. The estate-planning bar, private-wealth advisers, and many wealthy donors oppose limits; ProPublica reporting has shown widespread use of these techniques among top fortunes, and lobbying to preserve them is consequential. 

5) Offshore profit shifting, deferral, and preferential international rules

What it is. Multinationals use transfer pricing, licensing, and offshore subsidiaries to shift reported profits to low-tax jurisdictions and to defer U.S. tax. The TCJA and subsequent rules (GILTI/FDII, BEAT, global minimum tax) changed the landscape but sizeable loopholes remain.
Revenue cost. JCT/Treasury list “reduced tax on active foreign-source income” and related items among the larger business tax expenditures (tens of billions in a typical year — e.g., JCT estimated certain CFC preferential treatments at $46.3 billion in 2024 for one item). Broader estimates of revenue leakage from profit shifting run into the tens of billions annually. 
Who defends it. Big multinationals, tech and pharma companies, and big accounting/law firms litigate and lobby strongly to preserve low-tax routing options or to shape new rules (and they retain a steady presence in Treasury and congressional consultations). The Treasury and IRS have separately targeted abusive partnership transactions and estimate anti-abuse work could raise $50+ billion over a decade. 

Why these survive: the lobbying and political economy

Two features explain persistence: (1) concentrated benefits, diffuse costs. The handful of wealthy families and firms that benefit lobby intensely; the billions in revenue lost are spread thinly across all taxpayers and years, so public pressure is muted. (2) technical complexity. Carving back exemptions requires detailed drafting and imposes compliance—or political—costs that produce fierce industry opposition. OpenSecrets and reporting show private-equity, real-estate, and financial industries spend heavily to defend the specific breaks that serve them. 

Bottom line

If lawmakers wanted to raise revenue from wealthy interests they could prioritize closing or narrowing a relatively short list of provisions that primarily advantage the affluent: carried-interest treatment, the step-up in basis, aggressive GRAT/ grantor-trust techniques, broad 1031 deferrals, and certain cross-border profit-shifting rules. Together those reforms could plausibly raise tens to hundreds of billions over a decade, depending on scope and baseline assumptions — which is why the beneficiaries invest heavily in lobbying to keep them.