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GRAT vs. IDGT vs. Portability on a $10M Estate: Why This Week's Rate Jump Costs GRATs $613K More Than IDGTs

The number that moved this week (and why it matters to your estate plan)

NerdWallet's mortgage desk reported something unusual this week: rates rose not because inflation is hot, but because the Fed chair sounded hawkish and fighting flared up again in Iran. Markets read both as reasons to expect a rate hike, and mortgage rates climbed in response ("Mortgage Rates Rise This Week as Markets Anticipate Fed Hike," NerdWallet).

Here's the part that doesn't make headlines: the same Treasury yield move that pushed mortgage rates up also feeds directly into the IRS Section 7520 rate — the hurdle rate that determines whether a GRAT (Grantored Retained Annuity Trust) or an IDGT (Intentionally Defective Grantor Trust) sale actually transfers wealth tax-free. When mortgage rates jump 25-40 basis points in a week, so does the rate your estate attorney is going to plug into your GRAT annuity calculation.

Meanwhile, the labor market is sending the opposite signal. The BLS's latest release shows payroll employment fell by 23,000 in July, CPI rose just 0.1%, and unemployment sits at 4.1% ("Major Economic Indicators Latest Numbers," BLS). That's a soft labor market with tame inflation — normally a setup for rate cuts, not hikes. The Fed hiking anyway, on geopolitical risk rather than economic overheating, is exactly the kind of environment where rates could reverse just as fast as they rose. That timing uncertainty is the whole ballgame if you're deciding whether to fund a trust this month or wait.

This is the kind of analysis Voritanel runs for you — so you don't have to build the spreadsheet yourself every time the Fed opens its mouth.

The worked example: $10M, 9% growth, and a rate that just moved

Let's say you're sitting on a $10 million concentrated position — pre-IPO stock, a family business stake, appreciated real estate — that you reasonably expect to grow at 9% annually over the next decade. You're deciding between three paths: a 10-year GRAT, an IDGT installment sale, or simply doing nothing and relying on portability between spouses.

Before this week: the 7520 rate sat around 4.6%. After this week's move: call it 5.0% — a 40 basis point jump, consistent with the scale of this week's mortgage rate increase.

That 40 basis points isn't cosmetic. Here's what it does to each strategy.

Strategy 1: The GRAT

A zeroed-out 10-year GRAT pays you back an annuity calculated so the present value equals your $10M contribution, using the 7520 rate as the discount rate. Anything the trust earns above that rate passes to your beneficiaries gift-tax-free.

Using the standard approximation — value transferred ≈ initial value × ((1+growth)¹⁰ − (1+hurdle)¹⁰) — here's the before-and-after:

Scenario7520 Rate(1+g)¹⁰(1+r)¹⁰Value Transferred
Before this week4.6%2.36741.5676$7,998,000
After this week5.0%2.36741.6289$7,385,000

That's a $613,000 swing in what your family actually keeps, purely from a week of Fed rhetoric and geopolitical news — before you've made a single decision about your own assets.

Strategy 2: The IDGT

An IDGT works differently. You typically seed the trust with a 10% gift ($1M) and sell the remaining 90% ($9M) to the trust in exchange for a promissory note priced at the Applicable Federal Rate — which runs meaningfully below the 7520 rate (the 7520 rate is set at 120% of the mid-term AFR). That gap is the reason GRAT vs. IDGT vs. Direct Gift on a $10M Asset tends to favor the IDGT once you account for it.

Using a 9-year note term and AFR estimates of 4.0% (before) and 4.3% (after) — a proportionally smaller move than the 7520 rate's jump:

ScenarioNote RateValue on $9M SoldSeed Gift Growth ($1M)Total Transferred
Before this week4.0%$6,736,500$2,172,000$8,908,500
After this week4.3%$6,400,000$2,172,000$8,572,000

The rate move still costs you money — $336,500 — but it's roughly half the damage the GRAT took. Two reasons: the note rate moves less than the 7520 rate in absolute terms, and the seed-gift portion of the trust is completely insulated from interest rate changes since it was never a loan in the first place. On top of that, IDGTs carry a "tax burn" advantage GRATs don't get as cleanly — the grantor pays the trust's income taxes out of pocket every year, which isn't treated as an additional gift, quietly compounding more wealth outside your taxable estate. That's not reflected in the table above, which means the real IDGT advantage is probably understated here.

If you want the mechanics behind why IDGTs tend to be more rate-resilient, When a GRAT Beats an IDGT (and When It Doesn't) walks through the break-even math in more detail.

Strategy 3: Do nothing, rely on portability

If you're married, the simplest option is to let your spouse's unused federal exemption port over to you — no trust, no annuity, no note. With a combined exemption around $30M for 2026 (2 × $15M), your $10M estate growing to $23.67M over 10 years at 9% never comes close to triggering federal estate tax.

But portability has a real cost that the GRAT and IDGT don't: the entire $23.67M stays inside your taxable estate. That matters for two reasons. First, if your estate grows faster than expected, or state estate tax applies (many states have exemptions far below the federal number), you could still owe something. Second — and this is the part people miss — assets that stay in your estate get a step-up in basis at death, erasing capital gains tax for your heirs. Assets you move into a GRAT or IDGT remainder trust generally don't get that same step-up, because they're no longer part of your estate. You're trading estate tax savings for a capital gains tax bill your heirs will eventually pay when they sell.

This is exactly the trade-off explored in The True Cost of Holding $12M in IPO Stock Until Death: sometimes keeping the asset in your estate and taking the step-up beats any amount of trust engineering, depending on your basis.

So which one actually wins?

Here's the honest answer: it depends on inputs you haven't told me yet.

  • If your estate is comfortably under the combined portability exemption and your assets have low basis (meaning big embedded capital gains), portability plus the step-up at death may beat both trust strategies outright — no legal fees, no annuity risk, no note administration.
  • If your estate is going to blow past the exemption — through growth, a liquidity event, or state estate tax exposure — the GRAT and IDGT gap matters, and as this week shows, that gap is sensitive to timing. Lock in a GRAT this week and you've frozen in a $613,000 worse outcome than if you'd funded it in August.
  • If you're worried the Fed reverses course once the soft payroll numbers work their way through the data, waiting could pay off — the 7520 rate is published monthly and could drop right back down. But you're betting on macro timing, not your estate plan.

None of this is a reason to panic into a trust before you've run your own numbers. The math above uses a 9% growth assumption and a 10-year horizon — reasonable for a diversified concentrated stock position, but if your asset is expected to grow at 12% (common for pre-IPO equity) or your horizon is 5 years instead of 10, every one of these numbers changes materially. You can model this for your specific situation at Voritanel rather than relying on someone else's growth assumption.

Why most people never run this math

NerdWallet's own research on financial confidence found that millions of Americans aren't confident they can even build a financial plan, let alone model a GRAT annuity against a moving 7520 rate ("How Making a Financial Plan Can Build Your Money Confidence," NerdWallet). That's understandable — the inputs are genuinely complicated, and most calculators either oversimplify (ignoring the rate sensitivity we just walked through) or require enough expertise that you need to hire someone just to use them.

It's a bit like the Citi AAdvantage Executive card bumping its bonus to 125,000 miles this week ("Citi AAdvantage Executive Welcome Bonus Soars to 125K Miles," NerdWallet) — the headline number looks great until you calculate the spending threshold required to actually earn it. Estate planning has the same trap: a $15M exemption or a "low" 7520 rate sounds good in the abstract, but whether it's good for you depends entirely on your growth assumptions, your basis, your state, and your timeline. For a broader framework on when to pull the trigger on any of these strategies, Should You Act on Estate Planning in 2026? lays out five concrete triggers worth checking against your own situation.

Run your own numbers before the rate moves again

The 7520 rate is published monthly, mortgage rates move weekly, and the Fed's next move is genuinely uncertain given the conflicting signals in the BLS data. Whatever you decide — GRAT, IDGT, or simply portability plus a step-up at death — the difference between the right answer and the wrong one for your family comes down to your specific growth assumption, your basis, your state, and your time horizon, not a generic rule of thumb.

Run the actual numbers for your estate at Voritanel before you lock in a strategy based on this week's rate.

Sources

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