With a late spouse’s exclusion carried over
No gives $1,800,000. Yes — portability elected on their return gives $0 — a difference of $1,800,000 less (-100.0%).
Portability doubles the exclusion to $30,000,000, and it is lost unless an estate tax return was filed for the first spouse — a filing that is otherwise pointless and routinely skipped.
| Input | No | Yes — portability elected on their return |
|---|---|---|
| Gross estate(usd) | 20,000,000 | 20,000,000 |
| Debts, funeral and administration costs(usd) | 500,000 | 500,000 |
| Left to charity(usd) | 0 | 0 |
| Left to a spouse(usd) | 0 | 0 |
| Taxable gifts made in life(usd) | 0 | 0 |
| Using a late spouse’s unused exclusion | No | Yes — portability elected on their return |
| State estate or inheritance tax(percent) | 0 | 0 |
| Federal estate tax | $1,800,000 | $0 |
Every figure, both ways
| Step | No | Yes — portability elected on their return | Difference |
|---|---|---|---|
| Exclusion available | 15,000,000 | 30,000,000 | +15,000,000 |
| Deductions | 500,000 | 500,000 | 0 |
| Estate after deductions | 19,500,000 | 19,500,000 | 0 |
| Estate plus lifetime taxable gifts | 19,500,000 | 19,500,000 | 0 |
| Amount above the exclusion | 4,500,000 | 0 | -4,500,000 |
| Federal estate tax at 40% | 1,800,000 | 0 | -1,800,000 |
| State tax, at the rate you entered | 0 | 0 | 0 |
| Total tax | 1,800,000 | 0 | -1,800,000 |
| What reaches the heirs | 17,700,000 | 19,500,000 | +1,800,000 |
| Tax as a share of the estate(%) | 9.23 | 0 | -9.23 |
| Exclusion still unused | 0 | 10,500,000 | +10,500,000 |
Questions people actually ask
- Does lowering using a late spouse’s unused exclusion change the answer in proportion?
- The two sides differ by 100.0% in the answer. Read the step table below to see which line moves and which does not — that is where a formula stops being a black box.
- What is held constant between the two columns?
- Everything except using a late spouse’s unused exclusion: gross estate, debts, funeral and administration costs, left to charity, left to a spouse, taxable gifts made in life, state estate or inheritance tax. That is what makes the difference attributable — change two things at once and neither column tells you which one moved the answer.
- Can I compare my own two numbers?
- Yes, from the address bar: add ?a.portability=… and &b.portability=… to set each side, and a parameter without a prefix sets both at once. The page is computed per request, so any pair works — these two are only the ones worth a link.
Change either side by adding query parameters — ?a.portability=… and b.portability=…. A parameter without a prefix sets both sides at once. Source: IRS Revenue Procedure 2025-32 — basic exclusion amount $15,000,000 for 2026, annual gift exclusion $19,000, IRS — Estate tax, IRS — Frequently asked questions on estate taxes