Spouse Exemption and the Second-Death Window for Landlord Estates

The headline IHT-on-first-death story for a landlord couple is short. Section 18 IHTA 1984 gives an unlimited inheritance tax exemption on transfers between long-term-resident spouses or civil partners; on first death the entire portfolio passes to the surviving spouse tax-free, and the IHT400 reports a chargeable estate of zero. The complication is the second death. The portfolio has consolidated in the surviving spouse's hands, and the next time the IHT door opens, it opens on the whole estate with no spouse to pass through.

This page is the window between those two deaths. It covers the spouse-exemption mechanics that defer the first-death charge, the limited £325,000 cap that applies where the receiving spouse is not long-term resident (and the section 267ZA election that switches it off), the transferable NRB and RNRB claim mechanics on IHT402 and IHT436 within 2 years of the second death, and the surviving spouse's decision tree for the period between the deaths: gift down in lifetime under the 7-year PET clock, redirect via a deed of variation in the 2-year section 142 window, strip value through a charitable legacy, or accept the second-death exposure and plan liquidity with life cover in trust. The page closes on two worked examples for portfolios at £1,500,000 and £2,800,000.

What section 18 actually does (and what it does not)

Section 18(1) IHTA 1984 reads: "A transfer of value is an exempt transfer to the extent that the value transferred is attributable to property which becomes comprised in the estate of the transferor's spouse or civil partner." The provision applies to lifetime transfers and to transfers on death, and there is no upper limit on the value transferred between two long-term-resident spouses. A landlord couple with a £3,000,000 combined estate can pass the entirety from the first dying to the survivor with no IHT consequence at the first death.

What section 18 does not do is move the underlying asset out of the IHT regime. The portfolio that passes to the survivor is in the survivor's estate from the moment it arrives. The IHT is deferred, not avoided. For a landlord couple, the consolidated estate after the first death is almost always larger than either standalone estate before the first death (the survivor now owns 100% of what was previously 50%-50%), and on the second death the IHT charge falls on the full consolidated value above the available NRB and RNRB allowances.

The exemption also does not extend to unmarried partners, however long-standing the relationship and however many children are shared. Cohabitee estates pay full IHT on transfers between partners on death; the only routes available to a cohabiting couple are the same routes available to any pair of unrelated individuals (annual exemption, lifetime gifts under the 7-year clock, charity legacy, life cover in trust). The marriage or civil partnership is the gating fact for section 18; conversion of a long cohabitation into a marriage or civil partnership unlocks the exemption from that date onward.

The non-long-term-resident spouse exception

From 6 April 2025 the historic domicile concept for IHT was replaced by a residence-based long-term-resident (LTR) test (per the Autumn Budget 2024 reform legislated in the Finance Act 2025). An individual is long-term resident for IHT purposes where either they have been UK resident for 10 of the previous 20 UK tax years, or they have been UK resident for 10 consecutive UK tax years (the two-route test set out at section 267A). The long-term-resident concept replaces the old "deemed domicile" and "domicile" framing entirely.

Where the transferring spouse is long-term resident but the receiving spouse is not, section 18(2) caps the spouse exemption at £325,000 (matching the current NRB amount). Above £325,000, transfers to the non-LTR spouse attract IHT on the same basis as transfers to a non-spouse. For a landlord couple where one spouse has been resident in the UK long enough to be LTR (typically the working-life spouse) and the other has spent recent years living abroad or has never been UK-resident, the consolidated portfolio that "obviously" should pass spouse-exempt on first death actually walks straight into a £1,000,000 or larger chargeable transfer.

The fix is section 267ZA. The non-LTR spouse can elect (in lifetime, or by the PRs within 2 years of the LTR spouse's death) to be treated as long-term resident for IHT purposes. The election lifts the £325,000 cap and the section 18 exemption becomes unlimited as it would be for two LTRs. The cost is that the electing spouse's worldwide assets are brought within UK IHT scope; for a non-LTR spouse holding limited overseas assets the trade is almost always worthwhile, for a non-LTR spouse holding material overseas wealth it requires careful modelling. Our long-term-resident IHT test page covers the residence test and the section 267ZA election in detail.

Why first-death relief is second-death exposure

The structural problem for landlord couples is consolidation. Before first death, each spouse typically holds 50% of the family home and 50% of the BTL portfolio (joint tenancy or tenancy in common). Each standalone estate is half the family wealth. After first death, with everything passing under section 18 to the surviving spouse, the survivor now holds 100% of the family wealth in one estate. The same asset base, the same total IHT exposure on death, but concentrated.

The headline £1,000,000 of combined allowances quoted in IHT advice (£325,000 NRB each + £175,000 RNRB each, transferable on second death) is preserved by the consolidation: the first deceased's unused NRB and RNRB transfer to the second-death estate via IHT402 and IHT436. That much is symmetric. What is not symmetric is the section 8D(5) RNRB taper at £2,000,000, which uses the gross value of the estate (E) at death, before any spouse or charity exemption. A standalone estate of £1,250,000 was nowhere near the wall; the consolidated £2,500,000 is £500,000 over it.

For a couple with a £700,000 family home and a £1,800,000 BTL portfolio split 50/50, the standalone first-death E is £1,250,000 (no taper, full RNRB available, but RNRB unused because the spouse exemption took the QRI off the table). On the survivor's second death, E is £2,500,000 (£500,000 over the threshold), the RNRB withdrawal is £250,000, and the resulting IHT on the lost allowance is £100,000. The full taper math is in the RNRB taper page; this page is the planning window before it bites.

The transferable allowances claim on second death

The PRs of the second deceased file two transferable-allowance claims alongside the IHT400 estate account: IHT402 for the transferable nil-rate band, IHT436 for the transferable residence nil-rate band. Both forms are filed within 2 years of the second death; HMRC commonly accepts late claims where the delay is reasonable.

IHT402 (TNRB). Section 8A IHTA 1984 carries the rule. The claim is the percentage of the first deceased's NRB that was unused on the first death, applied to the NRB at the date of the second death. Where the first death was wholly spouse-exempt (the default for a mirror-will landlord couple), the unused percentage is 100% and the second deceased's estate stacks £325,000 of own NRB + £325,000 of TNRB = £650,000 of combined NRB allowances. Where the first death used some of the NRB (a chargeable lifetime gift in the seven years before first death, or a non-spouse-exempt portion of the estate left to children), the unused percentage drops and the TNRB claim is correspondingly reduced. The percentage formula handles the case where the NRB amount has changed between the two deaths.

IHT436 (TRNRB). The mirror form for the residence nil-rate band, also a percentage-based claim. Where the first deceased's RNRB went unused (typical for a spouse-exempt first death), 100% of the first deceased's RNRB transfers. The transferable RNRB applies even where the first death pre-dated 6 April 2017 (when the RNRB was introduced); HMRC deems an RNRB to have been available for the calculation and the percentage applies as for post-2017 deaths. The transferable RNRB at the second death is then itself subject to the section 8D(5) taper test on the second-death E. A consolidated estate above £2,700,000 loses both the own RNRB and the transferable RNRB in full.

Practical procedural points the PRs should plan for. First, the first deceased's IHT200 / IHT400 records and the date of death certificate are needed to populate the IHT402 / IHT436 calculation; surviving spouses in their 80s or 90s, where the first death was 20+ years ago, sometimes struggle to locate these records. A "what we will need on second death" file built early in the second-death window is cheap insurance. Second, the 2-year filing window is from the second death, not the first; the PRs file the claims at the same time as the second-death IHT400. Third, the IHT435 (own RNRB claim) goes alongside IHT436; both forms reference the same QRI nomination and downsizing-addition position. The HMRC manual at IHTM43000 onwards walks the mechanics in detail.

The 2-year deed-of-variation window

Section 142 IHTA 1984 is the second 2-year clock relevant to the window. Within 2 years of the first death, a beneficiary of the first deceased's estate (in a typical mirror-will arrangement, the surviving spouse) can vary their entitlement and redirect it elsewhere, with read-back to the deceased for IHT (section 142) and for CGT (section 62(6) TCGA 1992). The variation must be in writing, signed by the beneficiary giving up the entitlement, for no consideration in exchange, and include an election that the read-back applies. The personal representatives of the first deceased must concur if the variation increases the IHT charge on the first-death estate.

For a landlord couple, the most common use is redirecting part of the first-death estate from the surviving spouse to the adult children. Effect: the redirected portion is treated as having passed direct from the first deceased to the children, uses the first deceased's NRB and RNRB at the date of first death (which otherwise would have transferred 100% to the second death), and reduces the consolidated estate the survivor inherits. The trade-off is the lost TNRB / TRNRB on second death (because the first-death allowances are now used, not unused), set against the lower second-death E and the preserved RNRB at second death (because the consolidated estate is now below the £2,000,000 wall).

The DoV calculation is fact-specific and often net-positive for estates in the £2,200,000 to £2,800,000 band, where moving £400,000 to £700,000 of value out of the survivor's hands drops second-death E below £2,000,000 and preserves a full £350,000 of combined RNRB. Above £2,800,000 and below £2,200,000 the calculation typically reverses (no taper saving to capture, or the lost TNRB / TRNRB at second death is worth more than the taper saving). Detailed DoV mechanics for landlord estates are covered separately in this Wave 4 series at the slug deed-of-variation-property-estate-redirecting-inheritance-iht-saving.

The surviving spouse's decision tree

Once the first death has settled and the consolidated estate is in the survivor's hands, four routes are available for the planning interval before second death. Each addresses the consolidation problem from a different angle.

• Lifetime gifting under the 7-year clock. The survivor gifts properties (or shares in a Family Investment Company holding the portfolio) to adult children or other intended beneficiaries as Potentially Exempt Transfers under section 3A IHTA 1984. Full IHT exemption if the survivor lives 7 years from the gift, with taper relief on the IHT due if death falls between years 3 and 7. The CGT cost (section 17 TCGA 1992 deemed disposal at market value, no section 165 holdover available for non-business BTL) is the trade-off. Best for survivors in their late 60s or early 70s with good health and material gains in the portfolio. Detailed mechanics at our 7-year-rule for lifetime property gifts page.
• Deed of variation in the first 2 years. Redirect part of the first-death estate to children directly, reading back to the first deceased and saving the survivor's RNRB at second death. Most effective in the £2,200,000 to £2,800,000 estate band. Time-limited: the 2-year clock starts on the first death, not on probate grant.
• Charitable legacy on second death. Where at least 10% of the relevant component of the estate passes to qualifying charity on second death, the IHT rate on the chargeable estate drops from 40% to 36% under Schedule 1A IHTA 1984. The mathematics often makes the gift self-funding in net family terms for estates above £2,000,000 where the RNRB has been lost to the taper. The charitable-legacy mechanics are covered in this Wave 4 series at the slug iht-charitable-legacy-property-portfolio-36-percent-reduced-rate.
• Accept second-death exposure, plan liquidity. Where lifetime gifting and DoV are unappealing or unavailable (survivor's age, portfolio liquidity, family circumstances), the conservative plan is to size the projected second-death IHT exposure and arrange whole-of-life cover written in trust to fund the IHT bill. The trust receives the policy proceeds outside the IHT estate; the trustees pay the IHT bill on second death; the descendants inherit the portfolio intact. Underwriting tightens with age; the policy is usually arranged during the first spouse's life rather than after first death.

The four routes are not mutually exclusive. A practical plan for a £2,500,000 consolidated estate often combines a modest DoV in the first 2 years (£300,000 redirected to children), a programme of lifetime gifting in years 3 to 10 of the window (£500,000 of BTL units gifted as PETs), and a backstop life-cover policy sized to the residual second-death exposure. The strategic-framework counterpart to this page is our IHT decision framework for landlords.

The April 2027 pension overlay

From 6 April 2027, unused defined-contribution pension funds and unused defined-benefit lump-sum death benefits enter the deceased's estate for IHT (Autumn Budget 2024 reform, draft Finance Act 2026). For a couple where the first death is post-April-2027, the surviving spouse's consolidated estate now includes any pension funds nominated to the survivor under beneficiary nomination, in addition to the property portfolio. The £2,000,000 wall is reached more quickly; the planning window between deaths is materially shorter in effective terms.

A couple at £1,800,000 of property + £600,000 of combined pensions sits comfortably below the wall on a current-rules death. On a post-April-2027 death the £2,400,000 gross E crosses the threshold by £400,000, withdraws £200,000 of RNRB on the survivor's death (assuming everything passed survivor-exempt on first death), and adds £80,000 of IHT. The second-death window planning conversation post-2027 must include the pension drawdown decision: pre-2027 wisdom was to leave pensions untouched and draw down the taxable BTL portfolio first; from 2027 the pension is also in IHT scope, and the case for drawing it down (or making lifetime gifts out of it where DC pension rules permit) is materially stronger. Our pension-IHT April 2027 page walks the decumulation sequencing implications.

Two worked windows

Smaller window: the Patels (consolidated £1,500,000)

Mr Patel dies 2026. Joint family home in Slough £550,000 (50/50), three BTL flats £600,000 net total (50/50), savings £100,000 in joint names. Mr Patel's standalone estate at first death: £625,000 (£275,000 home + £300,000 BTLs + £50,000 cash). The first-death estate passes wholly to Mrs Patel under section 18, no IHT, Mr Patel's £325,000 NRB and £175,000 RNRB both unused.

Mrs Patel's consolidated estate on first death: £1,250,000 (excluding any growth and any of her own subsequent assets). Even on a 2-3% per annum appreciation, the projected second-death E is £1,550,000 to £1,700,000 within 10 years. Below the £2,000,000 taper threshold throughout.

Second-death window assessment: the Patel estate is comfortably below the wall and likely to remain so. The transferable NRB and TRNRB claim on Mrs Patel's death stacks £325,000 + £325,000 + £175,000 + £175,000 = £1,000,000 of allowances against an estate that will probably be in the £1,500,000 to £1,700,000 band. Chargeable estate £500,000 to £700,000; IHT £200,000 to £280,000. Modest planning room (annual exemptions £3,000 each year, small-gifts £250 per recipient, perhaps modest charitable legacy on Mrs Patel's death) is enough. No DoV needed; no major lifetime gifts needed. The cheapest plan is the right plan: don't over-engineer where the taper does not bite.

Larger window: the Mawell-Smiths (consolidated £2,800,000)

Mr Mawell-Smith dies 2026. Joint family home in Reading £900,000 (50/50), seven BTL properties net portfolio £1,800,000 (50/50 via tenants-in-common), ISAs and cash £100,000. Mr Mawell-Smith's standalone first-death estate: £1,400,000. Wholly spouse-exempt; £325,000 NRB and £175,000 RNRB both unused.

Mrs Mawell-Smith's consolidated estate after first death: £2,800,000. On second death without any planning, the gross E of £2,800,000 exceeds the £2,000,000 threshold by £800,000, withdraws £400,000 of RNRB (which on the £350,000 of combined allowance fully extinguishes the RNRB), and produces an IHT charge of £820,000 (£2,800,000 minus £650,000 combined NRB = £2,150,000 chargeable at 40%).

Three planning moves available in the window. (1) DoV within 2 years of Mr Mawell-Smith's death redirecting £600,000 of the BTL portfolio to their two adult children. Effect: £325,000 of Mr Mawell-Smith's NRB used (no IHT on first £325,000 to children, £275,000 of further chargeable transfer reading back to Mr Mawell-Smith uses some of the surviving allowance, around £110,000 of IHT on the first-death IHT400). Mrs Mawell-Smith's E drops to £2,200,000; second-death E above £2,000,000 by £200,000, withdrawing £100,000 of RNRB (£250,000 RNRB preserved out of the £350,000 combined available, £40,000 less IHT than no DoV). (2) Lifetime gifting by Mrs Mawell-Smith of a further £400,000 in BTL value over 3 years post-first-death as PETs; if she survives 7 years from the gifts, second-death E drops to £1,800,000, the RNRB is fully restored, and combined IHT falls dramatically. CGT cost on the £400,000 of gifts at her marginal 24% rate is approximately £60,000 to £80,000 depending on inherent gain. (3) Whole-of-life cover in trust written for £200,000 to £400,000 to backstop the residual second-death exposure regardless of which other planning routes land.

The combined plan (DoV + lifetime PETs + backstop life cover) takes the worst-case second-death IHT charge from £820,000 to a range of £150,000 to £300,000 depending on Mrs Mawell-Smith's survival and the PET clock. The DoV must be executed within 2 years of Mr Mawell-Smith's death; the lifetime gifting must start as early as possible after first death (years on the clock matter more than year-on-year amounts); the life cover must be arranged early enough that Mrs Mawell-Smith's age and health do not make the premium prohibitive.

Closing pointers

The second-death window is the planning moment landlord couples should be active in. The first-death spouse exemption defers the IHT, it does not avoid it; the procedural mechanics on second death (TNRB / TRNRB claims on IHT402 / IHT436 within 2 years) are settled but the substantive decisions (DoV in the first 2 years, lifetime gifting under the 7-year clock, charity legacy, life cover) all have time-sensitive components and the routes that need the most lead time are the routes most consequential at scale.

Three priorities for a surviving spouse in a landlord couple in 2026. First, size the consolidated estate against the £2,000,000 RNRB taper threshold using the section 8D(5) gross-E methodology (full mechanics at the RNRB taper page). Second, decide whether a DoV in the first 2 years is worth executing and act before the window closes. Third, choose between lifetime gifting, charitable legacy and life cover for the residual exposure, on a basis that integrates CGT (section 17 TCGA disposal at MV on gifts), liquidity (the property is illiquid; the IHT charge is payable within 6 months of death), and family circumstances. The IHT decision framework for landlords page is the planning-lens companion to the procedural mechanics here.

External authority cited above: section 18 IHTA 1984 (legislation.gov.uk); section 8A IHTA 1984 (TNRB); section 267ZA IHTA 1984 (LTR election); section 142 IHTA 1984 (deed of variation); HMRC IHT402 (TNRB claim form); HMRC IHT436 (TRNRB claim form); HMRC IHTM43001 (transferable nil-rate band); Autumn Budget 2024 (NRB / RNRB freezes; pension-IHT 2027).