Whole of Life Assurance for IHT Planning: How the Mathematics Works

Whole of life assurance is, at its simplest, a policy that pays a guaranteed sum on death — whenever that death occurs. Unlike term assurance (which expires after a fixed period), a whole of life policy has no expiry date. If premiums are maintained, the policy pays out.

This certainty makes whole of life the natural tool for inheritance tax (IHT) planning. A predictable tax liability — emerging on death, whenever that happens — is well matched to a predictable payment — a death benefit payable on death, whenever that happens.

But "well matched" does not mean costless, and understanding the mathematics behind whole of life for IHT purposes is essential before recommending or accepting this strategy. The premium structure, the policy review mechanism, the policy's treatment in the estate, and the interaction with the taxpayer's overall estate planning position all affect whether whole of life genuinely makes financial sense and, if so, in what form.

This guide works through the mathematics step by step.

As of 2026, IHT rates and nil-rate bands are those current for the 2026/27 tax year. Changes legislated since the Autumn Budget 2024 — including the inclusion of unused pension funds within the IHT estate from 6 April 2027 (Finance Act 2026), and the reform of Business and Agricultural Relief from 6 April 2026 — may significantly affect the size of IHT liabilities and the planning strategies appropriate. Take current professional advice before proceeding.

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Step 1: Calculate the IHT Liability

Before selecting a whole of life policy, the IHT liability must be estimated. This requires a full estate valuation, which should include:

• Property (principal residence, investment property, overseas property)
• Investments (ISAs, share portfolios, investment bonds, cash)
• Business interests (shares in trading companies, partnership capital)
• Life assurance policies not in trust (included in the estate at their maturity/surrender value on death)
• Other assets (art, jewellery, vehicles, receivables)

Less:

• Outstanding mortgage and other debts
• Funeral expenses
• Charitable legacies (exempt from IHT)
• Assets passing to a spouse or civil partner (exempt from IHT — but this defers the liability, not eliminates it)

The net estate value, less the available nil-rate band(s), is the amount subject to IHT at 40%.

Example:

Item	Value
Main residence	£1,500,000
Investment property	£600,000
ISA and share portfolio	£800,000
Cash	£150,000
Life policies (not in trust)	£200,000
Gross estate	£3,250,000
Less mortgage	(£250,000)
Net estate	£3,000,000
Less nil-rate band (£325,000; RNRB tapered to nil — see below)	(£325,000)
Taxable estate	£2,675,000
IHT at 40%	£1,070,000

Note that the £175,000 residence nil-rate band is not available here: the RNRB is withdrawn by £1 for every £2 by which the estate exceeds the £2 million taper threshold, so it is fully tapered away once an estate reaches £2,350,000. At a net estate of £3,000,000 the RNRB is therefore lost entirely, leaving only the £325,000 standard nil-rate band.

In this example, the estate owes £1,070,000 in IHT. The question is how to fund this liability without forcing the heirs to sell assets under time pressure.

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Step 2: Select the Sum Assured

The sum assured on the whole of life policy should equal the IHT liability — in this case, approximately £1,070,000. However, several adjustments may be needed:

Allow for estate growth: If the estate is growing — through property appreciation, investment returns, or reinvested income — the IHT liability will increase over time. A policy written for the current liability may be insufficient by the time of death. Options include:

• An increasing sum assured (indexed to RPI or CPI, or a fixed annual percentage)
• A reviewable policy with a guaranteed insurability option allowing increases without fresh medical underwriting
• A combination of a fixed whole of life policy and additional term assurance providing coverage during the period of highest estate growth

Allow for the nil-rate band: The nil-rate band is £325,000 per person (frozen to April 2031), with an additional £175,000 residence nil-rate band (RNRB) for those leaving a main residence to direct descendants. The RNRB tapers away for estates above £2 million. Future nil-rate band changes — upward or downward — affect the liability. Do not assume the nil-rate band will increase.

Pension assets (from April 2027): The government announced in the Autumn Budget 2024 that pension assets (defined contribution pension funds remaining at death) will be brought within the IHT estate from April 2027. For individuals with significant pension accumulation, this will materially increase the IHT liability and therefore the required sum assured.

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Step 3: Understand the Premium Structure

Whole of life policies come in several premium structures, each with different financial characteristics:

Guaranteed Premium (Non-Reviewable)

The premium is fixed for the life of the policy. What you pay at outset is what you pay for ever. The insurer prices in a margin for the uncertainty of not being able to increase the premium.

Advantage: Certainty — premium budgeting is simple; no surprise increases in old age.

Disadvantage: Higher initial premium than reviewable alternatives; the insurer captures the pricing upside if the life assured lives longer than the statistical average.

Reviewable Premium

The premium starts lower than the guaranteed equivalent, but is reviewed by the insurer at regular intervals (typically every 5 or 10 years). At review, the insurer can increase the premium significantly — often by 50% to 200% or more, particularly at reviews after age 70 or 80. The review is based on the insurer's assessment of revised mortality tables and fund performance.

Advantage: Lower initial premium; may be lower overall if the life assured dies before a major review date.

Disadvantage: Significant uncertainty and the risk of premium escalation at an age when fixed-income may be constrained.

For IHT planning purposes, reviewable policies are generally unsuitable — the risk of premium increases creating financial hardship in old age undermines the planning objective. The default recommendation for IHT-planning whole of life is guaranteed premium.

Joint Life, Last Survivor (JLLS) Policy

Most commonly used for IHT planning by couples. The policy insures two lives and pays on the second death — which is typically when the IHT liability crystallises (assets passing between spouses are IHT-exempt on first death).

Illustration (couple, male aged 55, female aged 52, non-smokers):

For a JLLS whole of life policy paying £500,000 on second death, as a rough indicative figure (actual premiums depend on underwriting, provider, and policy terms), monthly premiums might range from approximately £450 to £700 per month for healthy, standard risk applicants. This represents a total annual outlay of £5,400 to £8,400 per annum.

These are illustrative figures only. Actual premiums require individual underwriting and will vary by insurer, health status, and policy terms. Do not rely on these figures for planning purposes.

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Step 4: The Break-Even Analysis

A common question is: "At what point does the whole of life policy 'break even' — i.e., pay out more than it cost in premiums?"

The answer depends on how long the life assured (or survivor, in a JLLS policy) lives.

Illustration:

• Sum assured: £500,000
• Annual premium: £7,200 (£600/month)
• Couple currently aged 55 (male) / 52 (female)

Year	Age of survivors	Total premiums paid	Surplus over premiums
10	65/62	£72,000	£428,000
20	75/72	£144,000	£356,000
30	85/82	£216,000	£284,000
40	95/92	£288,000	£212,000
50	105/102	£360,000	£140,000

As this illustration shows, even with 50 years of premiums, the policy pays out significantly more than it costs in premiums — because life assurance is a pooling mechanism and the policy is leveraged against mortality risk.

However, the correct comparison is not simply total premiums vs. sum assured. The relevant comparison for IHT planning is the cost of the premium vs. the tax saved:

• IHT funded: the £500,000 death benefit (paid free of IHT when written in trust) provides £500,000 of cash towards the roughly £1,070,000 liability — meeting close to half of it without the heirs having to liquidate assets
• Annual opportunity cost of premiums: £7,200 invested at (say) 5% per annum = a growing investment pot that would eventually exceed £500,000 if the couple live long enough

This is why whole of life is genuinely efficient for IHT planning: the tax saving is the "return on investment", and the question is whether the tax saving exceeds the total cost of premiums plus the opportunity cost of the investment. For most families with a predictable IHT liability, the answer is yes — particularly where the liability will not diminish (i.e., where the estate continues to grow).

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Policy Written in Trust

A whole of life policy for IHT planning must be written in trust. If the policy is not in trust, the proceeds are paid into the estate — and are themselves subject to IHT. This would defeat the entire purpose.

For a joint life last survivor policy, a discretionary trust with the children and remoter issue as potential beneficiaries is the standard arrangement. The couple (as settlors) can complete a letter of wishes to guide the trustees, but the discretionary trust structure allows flexibility at the time of the second death.

See the related guide on trust deed drafting for international families for the mechanics of establishing and reviewing the trust.

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IHT Planning Alternatives — and Why Whole of Life Complements Them

Whole of life assurance for IHT is not the only strategy, and is most effective as part of a broader plan:

• Gifting: Assets given away survive 7 years (potentially taper relief applies) and fall outside the estate. But gifting requires giving up control of assets.
• Business Relief (BR): Qualifying business and agricultural assets attract 100% relief, but from 6 April 2026 the 100% rate is capped at £2.5 million per individual (transferable between spouses); value above the cap attracts 50% relief (a 20% effective IHT rate). AIM-listed and other unlisted shares qualify for 50% relief only and fall outside the £2.5 million allowance. BR can be used deliberately by investing in qualifying companies, but the post-2026 caps materially limit its use as an open-ended IHT shelter.
• Pension funding: Pension assets have been sheltered from IHT historically, though this is changing from April 2027.
• Trusts: Settling assets into trust removes them from the estate (subject to seven-year rules and the trust's own IHT regime).

Whole of life assurance is typically used to cover the residual IHT liability after all available reliefs and exemptions have been applied — providing a guaranteed, certain payment to HMRC without requiring heirs to liquidate assets.

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How Global Investments Can Help

Global Investments provides whole of life IHT planning as part of a comprehensive estate planning review. We begin by calculating the client's current and projected IHT liability, identify all available reliefs and exemptions, model the impact of different planning strategies, and recommend a whole of life structure calibrated to cover the residual liability efficiently.

We work with specialist tax solicitors and trust lawyers to ensure the policy is written in trust correctly, and we review the arrangement annually to ensure it remains adequate as the estate value changes.

For internationally mobile clients with assets in multiple jurisdictions, we also advise on the interaction of UK IHT with overseas succession taxes and help structure the overall estate plan accordingly.

Contact Global Investments to arrange an IHT review.

IHT rates, nil-rate bands, and pension death benefit treatment may change. The information in this guide reflects the position as of 2026. Always take current professional advice.