NOT financial advice - seek advice from a professional for your specific situation

    TaxKilnUK tax guidance
    TaxKilnUK tax guidance

    Divorce + tax → Cohabitation tax gap

    Cohabitation Tax Gap — No Spouse Exemption + Common-Law-Marriage Myth Debunked

    Cohabiting couples — regardless of relationship duration — have NO spouse-exemption framework in UK tax. The 'living together' test in TCGA 1992 s.288 is restricted to married couples + civil partners and does NOT extend to cohabitees. Transfers between cohabitees are full-market-value disposals: full CGT on the transferring partner's gain. There is no Pension Sharing Order mechanism — each retains their own pension. There is no IHT spouse exemption on first death — full IHT charge above NRB / RNRB. There is no Marriage Allowance. TOLATA 1996 (Trusts of Land and Appointment of Trustees Act), constructive trust, and proprietary estoppel provide LEGAL remedies for unwinding shared property — but these are equitable / property law mechanisms, NOT tax advantages. The 'common-law marriage' myth — that long-term cohabitees acquire rights equivalent to marriage — has no basis in UK law.

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    Guidance, not advice. We explain the rules, we don't assess your situation. Always seek financial or tax advice from your accountant, or contact HMRC. Read our editorial scope →

    In plain English

    This is the most editorially-important page in this cluster. The single most damaging myth in UK family + tax law is that long-term cohabiting couples acquire 'common-law marriage' rights after a certain number of years. They do not. There is no such concept in English or Welsh law. Cohabitees who have lived together for 30 years have exactly the same legal + tax status as cohabitees who have lived together for 30 days. What does this mean in practice? CAPITAL GAINS TAX: Transfers between cohabitees are full-market-value disposals. If you and your unmarried partner jointly own a buy-to-let and you transfer your half to them on separation, you trigger CGT on your gain at market value. Married couples + civil partners would have no-gain-no-loss treatment under TCGA 1992 s.58 (extended by FA 2023 to 3 tax years post-separation + court-ordered indefinite extension). Cohabitees: none of this. Full CGT, full market value, no relief. PENSIONS: There is no Pension Sharing Order for cohabitees. Each partner retains their own pension. If one partner has been the higher earner with significant pension accrual and the other has been the lower earner / homemaker with little pension, separation crystallises that asymmetry permanently. Married couples can split via PSO (Welfare Reform and Pensions Act 1999 ss.27-51). Cohabitees cannot. INHERITANCE TAX: There is no spouse exemption on first death. If your unmarried partner dies and leaves you their estate, IHT is charged at 40% above the NRB (£325k) + RNRB (£175k where home passes to lineal descendants). Married couples + civil partners get unlimited spouse exemption. Cohabitees get nothing. MARRIAGE ALLOWANCE: Not available. Cohabitees cannot transfer 10% of Personal Allowance to a partner. What legal options exist on cohabitation breakup? TOLATA 1996 (Trusts of Land and Appointment of Trustees Act): allows the court to determine beneficial ownership of jointly-owned property + order sale. Useful for disputed shares in property; NOT a tax relief. CONSTRUCTIVE TRUST: where one partner has contributed to the acquisition / improvement of the other's property, the court may impose a constructive trust giving them an equitable interest. Equitable; needs evidence. NOT a tax relief. PROPRIETARY ESTOPPEL: where one partner has been induced to act to their detriment in reliance on a promise of property rights, the court may grant a proprietary remedy. Equitable; high evidence bar. NOT a tax relief. None of these are tax advantages. They are legal mechanisms for sorting out shared property — they do not give cohabitees the tax-favoured treatment that married couples enjoy. Resolution + the Law Society have been campaigning for cohabitee legal reform for over 15 years — no significant statutory change to date. Until reform, cohabitees should: (i) understand they are NOT married; (ii) document property ownership clearly (declaration of trust); (iii) consider cohabitation agreement; (iv) recognise the structural disadvantage on separation + first-death IHT.

    How it works

    Why cohabitees fall outside the spouse exemption framework

    Every spouse-exemption provision in UK tax law is restricted to married couples + civil partners. TCGA 1992 s.58 (no-gain-no-loss): 'spouses or civil partners'. WRPA 1999 ss.27-51 (PSO): triggered by divorce / dissolution. IHTA 1984 s.18 (IHT spouse exemption): 'transfer between spouses or civil partners'. ITA 2007 ss.55A-E (Marriage Allowance): 'married couple or civil partnership'. The 'living together' test in TCGA s.288 is restricted to married couples in respect of s.58. There is no mechanism by which cohabitation duration converts cohabitees into spouses for tax purposes. The statutory language is explicit and exclusive.

    CGT on cohabitee transfers

    Full-market-value disposal. Transferring partner triggers CGT on the gain from base cost to current market value. AEA available (£3,000 in 2025/26). Residential property 24% higher-rate; 18% basic-rate (within band). Other assets 24% / 18%. 60-day reporting required for residential property. No £58 relief. No FA 2023 extension. The fact that the couple have lived together for 30 years is irrelevant.

    Pensions on cohabitee separation

    No mechanism for pension splitting. Each partner retains their own pension. The higher-earner partner does not have to transfer any pension value to the lower-earner partner. There is no PSO; no PAO; no offsetting framework imposed by court (unlike divorce financial-remedy proceedings). Where one partner has been the homemaker / lower-earner with minimal pension accrual, separation crystallises that asymmetry permanently. This is the single most-damaging consequence of the cohabitation framework in long relationships.

    IHT on cohabitee first death

    No spouse exemption. Estate passing from one cohabitee to the other is fully chargeable above NRB (£325k) + RNRB (£175k where home passes to lineal descendants — note: cohabitee surviving partner is NOT a lineal descendant and may not qualify for RNRB on home passing to them). Large-estate cohabitee couples face significant IHT exposure on first death where married couples face none. Will-planning and lifetime giving + PETs are the standard workarounds, but they are workarounds — not equivalent to spouse exemption.

    These are LEGAL remedies for unwinding shared property arrangements between cohabitees. They are not tax reliefs. TOLATA 1996: court determines beneficial ownership shares of jointly-owned property; can order sale + distribution. Used where co-ownership is disputed. Evidence required: declaration of trust, contributions to purchase / mortgage / improvements, intention evidence. Constructive trust: court imposes equitable interest where one partner has contributed to acquisition / improvement of the other's property in reliance on a common intention of shared ownership. Stack v Dowden + Jones v Kernott frameworks. Evidence-heavy. Proprietary estoppel: court grants property remedy where one partner has been induced to act to their detriment in reliance on a promise of property rights. Thorner v Major framework. High evidence bar. None of these mechanisms produce tax advantages. A constructive-trust interest awarded by the court is still acquired at market value for CGT — the cohabitee gets a beneficial interest, not a no-gain-no-loss transfer.

    Cohabitation agreement — the practical mitigation

    Cohabitees can — and should — enter into a cohabitation agreement before separation: declaration of trust over shared property; provision for separation contingency; agreed pension contributions / equalisation funded from joint income during relationship. This does not give tax advantages but it does give legal certainty. For large-estate cohabitees: marriage / civil partnership is the only tax-favoured option. The decision to remain unmarried is personal — but it has tangible tax consequences that need to be understood.

    Who this applies to + key conditions

    Statute + manual references

    Primary: TCGA 1992 s.288 ('living together' definition restricted to married couples + civil partners); WRPA 1999 ss.27-51 (PSO — marriage / dissolution only); IHTA 1984 s.18 (spouse exemption — marriage / civil partnership only); ITA 2007 ss.55A-55E (Marriage Allowance — marriage / civil partnership only); Trusts of Land and Appointment of Trustees Act 1996 (TOLATA — equitable mechanism, not tax relief).

    Related: Civil Partnership Act 2004 (civil partnership equivalent of marriage); Marriage (Same Sex Couples) Act 2013; Family Law Act 1996 (some non-tax cohabitee protection); Inheritance (Provision for Family and Dependants) Act 1975 (cohabitee discretionary claim against deceased's estate — limited)

    Case law: Stack v Dowden [2007] UKHL 17 (constructive trust quantification for cohabitees); Jones v Kernott [2011] UKSC 53 (further constructive trust framework); Thorner v Major [2009] UKHL 18 (proprietary estoppel)

    Common mistakes + traps

    Worked example

    Helen + James, cohabiting 15 years (never married), joint assets approximately £480k including jointly-owned property, separate pensions

    Joint flat (jointly owned 50/50): £350k value, £210k base cost (£140k gain in total); each partner's 50% share carries £70k gain. James's pension (DC, £180k value, accrued during relationship from his £85k salary). Helen's pension (DC, £45k value, accrued from £28k part-time during relationship). Shared savings £50k. Separation: Helen to keep the flat (buys James out at market value); James keeps pension intact.

    1. Flat buy-out: James transfers his 50% (£175k value) to Helen for £175k cash. James's CGT on transfer: £70k gain — less £3k AEA = £67k chargeable. At 24% residential higher-rate: £16,080 CGT. 60-day reporting required.
    2. Married couple alternative: s.58 no-gain-no-loss; James transfers tax-free, Helen inherits combined base cost. Cohabitee outcome: £16,080 CGT bill on the transfer.
    3. Pension asymmetry: James retains £180k pension. Helen retains £45k pension. £135k pension value gap. NO mechanism to split. Helen cannot claim PSO. Married couple alternative: court could order PSO transferring up to £67.5k of James's pension to Helen for equalisation. Cohabitee outcome: Helen permanently disadvantaged.
    4. Shared savings £50k: split 50/50 by agreement. No tax consequences (cash transfer).
    5. Hypothetical first-death: assume James dies year after separation with £180k pension + £200k other assets = £380k estate; passes to children. NRB £325k + (no RNRB if not passing to lineal descendant home interest). Chargeable £55k @ 40% = £22k IHT.
    6. Hypothetical IHT if James + Helen had been married and stayed together: James's estate to Helen, full spouse exemption, zero IHT on first death; later passing to children with double NRB + RNRB transfer.

    Outcome: Cohabitation framework cost Helen: (i) £16,080 CGT on flat transfer; (ii) £67.5k missing pension value (would have been transferred via PSO if married); (iii) no IHT spouse exemption on hypothetical first death. Combined £83k+ disadvantage on this £480k position purely from being unmarried. The 15-year relationship duration is irrelevant — same outcome as 15 weeks.

    How this connects to the rest of the framework

    CGT spouse exemption (FA 2023) →

    Married couples + civil partners get FA 2023 extended s.58 relief — cohabitees get nothing equivalent.

    Pension splitting (PSO/PAO/offsetting) →

    PSO is restricted to married couples + civil partners — cohabitees cannot split pensions on separation.

    IHT implications + LTR →

    IHT spouse exemption is restricted to married couples + civil partners — cohabitee first-death faces full IHT charge.

    Marriage Allowance termination →

    Marriage Allowance is restricted to married couples + civil partners — cohabitees cannot transfer PA.

    Scenarios + anti-charlatan →

    Cohabitation breakup scenario (£5m joint assets, 15-year relationship) shows full impact.

    /tax-reliefs/principal-private-residence →

    PPR available to cohabitees on their own main residence — but no s.225B extension on transfer to ex-partner.

    Frequently asked questions

    What happens if I miss the Self Assessment deadline?+
    The Self Assessment deadline is 31 January (online filing) for the previous tax year. Miss it and HMRC apply an automatic £100 penalty. Beyond that: £10 per day from 3 months late (capped at £900), 5% of tax due at 6 months late, and another 5% at 12 months late, under Schedule 55 of the Taxes Management Act 1970. If you have a genuine reason (serious illness, bereavement, technical issue with HMRC's systems) you can appeal with evidence; HMRC accepts reasonable excuse appeals in most genuine cases.
    Do I need an accountant or can I file Self Assessment myself?+
    Legally you can file Self Assessment yourself via gov.uk for free, most simple sole-trader returns (single income source, basic expenses) are realistic to self-file. An accountant adds real value when: your trading profit is above £40,000 (extraction-strategy decisions matter), you have multiple income streams (PAYE + self-employment + property + dividends), you've crossed the £90,000 VAT threshold, you're considering incorporation, or you have an HMRC enquiry. Expect to pay £400-£1,500/year for a typical sole-trader accountant; the cost is itself a deductible expense.
    How do payments on account work?+
    When your Self Assessment tax bill exceeds £1,000 for the first time, HMRC requires payments on account toward NEXT year's tax. Half the current bill is due 31 January (alongside the current bill); the other half is due 31 July. So your first January after crossing the threshold can hit with a double-bill: last year's balance + first payment on account. Adjust via Form SA303 if you expect next year's income to drop substantially. Payments on account don't apply if more than 80% of your tax is collected via PAYE.
    Does common-law marriage give cohabitees spouse exemption?+
    No. Common-law marriage is a myth in English + Welsh law. It does not exist. Cohabitees acquire NO spouse-exemption rights regardless of relationship duration.
    Can a cohabitee claim against a deceased partner's estate?+
    Yes — under the Inheritance (Provision for Family and Dependants) Act 1975, a cohabitee living with the deceased for at least 2 years can apply to court for discretionary provision. This is a court claim — NOT spouse exemption. The estate still faces full IHT on first death.
    What's the difference between cohabitation and civil partnership?+
    Civil partnership (Civil Partnership Act 2004 + 2019 extension to opposite-sex couples) is the legal equivalent of marriage for tax + inheritance purposes — full spouse exemption + PSO + Marriage Allowance. Cohabitation is no legal status — no tax-favoured treatment.
    Should we get married just for the tax?+
    Personal decision. For large-estate couples, the tax differential can be significant — particularly IHT on first death. We don't offer financial advice, but the framework is clear: marriage / civil partnership = spouse exemption; cohabitation = no spouse exemption. Quantify your specific position before deciding.

    Free + regulated-body resources

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