What Mamdani’s Estate Tax Proposal Could Mean for New York Estate Planning

For many New Yorkers, estate tax planning has felt like something that could wait. Under current law, that reaction is understandable. New York’s basic exclusion amount for 2026 is $7.35 million, which means many families and business owners still feel comfortably outside the state estate tax conversation.

That is why the recent proposal linked to New York City Mayor Zohran Mamdani has drawn so much attention. Recent reporting indicates the proposal would reduce New York’s estate tax threshold to $750,000 and raise the top rate to 50%. It is not current law, and it would likely change materially if it ever moves through an actual legislative process. But it reflects a real appetite to raise revenue and gives taxpayers a preview of the kinds of transfer tax approaches New York policymakers may be willing to consider.

Why the Proposal Matters Even Before It Becomes Law

Even if this proposal never becomes law in its current form, it still tells New York families and their advisors something useful. It suggests that higher‑revenue wealth transfer ideas remain firmly in the policy conversation and that thresholds many clients have come to rely on should not be treated as permanent planning assumptions.

That matters most for clients whose wealth does not always feel like “estate tax wealth.” A house, modest investment assets, retirement accounts and an interest in a private business can build into a substantial estate without any single event making the exposure obvious. When a proposal suddenly drops the threshold from $7.35 million to $750,000, it gets attention because it shows how quickly the conversation can change.

In that sense, the proposal is important even if it changes. Review the planning now, while the options are still open.

Current New York Mechanics Still Matter

Under current law, New York’s 2026 exclusion is $7.35 million, the estate tax return is due within nine months after death, and New York continues to apply a three‑year addback rule for certain taxable gifts made before death, currently extended through estates of decedents dying before January 1, 2032. Those features already make timing and structure matter more than many clients realize.

The proposal does not create the need for planning from scratch. It simply shines a brighter light on a planning environment that already requires care.

The New York Cliff, in Dollars

For 2026, the exclusion amount is $7.35 million. The top of the cliff band is 105% of that amount, or $7,717,500. If a taxable estate is at or below $7.35 million, there is generally no New York estate tax because the available credit offsets the tax. If the taxable estate rises above $7.35 million, that credit begins to phase out. Once the estate exceeds $7,717,500, the benefit of the exclusion is gone, and for $1 over that amount, the estate will owe hundreds of thousands of dollars in taxes.

That is the current law. The Mamdani proposal simply makes the broader lesson harder to ignore.

Current New York Estate Tax Mechanics and the “Cliff” Explained

New York’s estate tax rules remain crucial for effective planning. As of 2026, the state’s exclusion amount is $7.35 million, with estate tax returns due within nine months of death. New York also enforces a three-year addback rule for certain taxable gifts made before death, currently extended for estates of decedents dying before January 1, 2032. These requirements make timing and structure more important than many realize, even before any new proposals take effect.

The exclusion amount creates a “cliff” effect: estates at or below $7.35 million generally owe no New York estate tax, as the available credit cancels out the tax. However, once a taxable estate exceeds $7.35 million, the credit starts to phase out. If the estate surpasses $7,717,500 (105% of the exclusion), the exclusion is lost entirely, and even one dollar over this amount triggers estate taxes totaling hundreds of thousands of dollars. This is the current law, and proposals like Mamdani’s—which would lower the threshold and increase rates—highlight the need for careful planning in an environment where the stakes can change rapidly.

Why the Proposal Changes the Planning Conversation

The reported proposal would lower the threshold significantly. If that happens, many families who have never viewed themselves as exposed to state estate tax would be pulled directly into the conversation, including closely held business owners and families with valuable but illiquid assets.

Even if the exact proposal changes, it shows the kinds of approaches New York may be willing to consider. For clients with growing estates, that alone is reason enough to evaluate whether today’s planning still works if tomorrow’s environment becomes less forgiving.

Example One: No Planning Under the Proposal

Assume a New York business owner dies owning:

Home: $400,000
Investment account: $500,000
100% interest in a closely held business: $700,000
Total estate: $1,600,000

Under the working assumption above, this estate is above the proposed threshold and top of the phaseout band. For illustration, the estate is therefore treated as fully beyond the cliff and taxed on the full taxable estate at 50%.

Illustrative New York estate tax: $1,600,000 × 50% = $800,000

Now look at liquidity. The estate has $500,000 of readily liquid investment assets. The home is not a practical source of immediate cash. The business may be valuable, but it is not automatically liquid on the timetable an estate needs. If the estate is facing an illustrative New York estate tax of $800,000 and has only $500,000 of liquid assets, the shortfall becomes clear.

The family may need to borrow, negotiate a redemption under pressure or sell part of the business at exactly the wrong time.

Example Two: Two 33% Gifts

Assume the owner transfers two 33% noncontrolling interests in the business during life to irrevocable trusts for descendants, outside New York’s three‑year addback window. The owner retains the remaining 34% interest, subject to discounts for lack of control and marketability.

The post‑gift estate at death now looks like this:

Home: $400,000
Investment account: $500,000
Remaining 34% business interest: $155,000
($700,000 × 34% × (1 – 35% DLOC/DLOM))
New total estate: $1,055,000

This estate is still above the assumed $787,500 top of the phaseout band and is again modeled as fully beyond the cliff and taxed on the full taxable estate at 50%.

Illustrative New York estate tax: $1,055,000 × 50% = $527,500

Without planning, the owner dies holding 100% of the business, and the estate carries the full exposure. With lifetime gifts, part of that value is shifted earlier, while planning is still available and before future appreciation continues building inside the estate.

The planning did not require a massive company or a public market exit. It simply required identifying a growing asset, structuring the transfers while the owner was alive, and supporting the value correctly.

Why Valuation Matters

A lifetime gift only works if the value of what was transferred can be supported. A noncontrolling interest in a private business must be valued based on the fair market value of the specific interest transferred, on the specific date of transfer, based on the actual facts and circumstances surrounding that ownership block.

It is not just about what the overall company may be worth. It is about what this particular interest is worth, based on expected cash flow, market evidence, the rights attached to the interest, degree of control, lack of liquidity, transfer restrictions, governing documents and distribution rights.

If the value is inflated, the client may use more federal exemptions than necessary. If the value is understated, the transfer may create audit risk and weaken the planning.

A properly supported gift of two 33% interests can move meaningful value out of the estate and shift future appreciation with it. But that only works if the underlying valuation is disciplined, defensible and tailored to the actual interests being transferred.

The Better Takeaway

The Mamdani proposal is not current law and may never become law in this exact form. But it suggests the direction New York may move in order to raise revenue.

That is enough reason for families with growing estates, closely held businesses or concentrated illiquid assets to review their planning now.

The right questions are not complicated. What is the estate worth today? How much of that value is tied to a growing business? How much liquidity would the estate actually have if tax were due? And should some of that value be shifted during life, while there is still time to do it thoughtfully?

Those are the questions that matter under current law. They matter even more if New York keeps moving in this direction.