UK Income Splitting 2026/27: How Couples Can Legally Reduce Their Tax Bill

What Is Income Splitting?

Income splitting is the practice of arranging affairs so that taxable income falls in the hands of the lower-taxed partner in a couple rather than the higher-taxed one. The UK tax system taxes individuals, not households, which creates opportunities for couples where one partner pays higher-rate (40%) or additional-rate (45%) tax and the other pays basic-rate (20%) tax or has unused Personal Allowance (£12,570 in 2026/27).

The potential savings are significant. Moving £10,000 of income from a 40% taxpayer to a 20% taxpayer saves £2,000 in income tax per year. Moving £10,000 from a 45% taxpayer to someone with unused Personal Allowance saves £4,500.

HMRC is aware of income-splitting strategies and has specific anti-avoidance rules — primarily the settlements legislation (ss620–648 ITTOIA 2005) — to counteract arrangements that are contrived or lack commercial reality. The techniques described in this guide are all legitimate when implemented correctly.

Marriage Allowance: £252/yr Saving

Marriage Allowance is the simplest and most widely available income-splitting tool. It allows a spouse or civil partner who earns below the Personal Allowance (£12,570) to transfer £1,260 of their unused allowance to their partner — reducing the recipient's tax bill by £252 per year (£1,260 × 20%).

Crucially, Marriage Allowance is not available if the higher earner pays tax at the higher or additional rate. This means couples where one partner earns over £50,270 cannot use this specific relief. In that case, other strategies described below are more relevant.

If you have not claimed and are eligible, you can backdate claims to 2022/23, potentially generating a lump sum refund of up to £1,008 (4 × £252). The lower earner applies and can choose to receive the refund as a cheque or bank transfer, or have the recipient's tax code adjusted.

Joint Savings, Investments and Form 17

HMRC's default rule for jointly held assets is a 50/50 income split, regardless of who contributed the money. This is often advantageous — if the higher earner put in 100% of the capital into a joint account, HMRC still taxes only 50% of the interest on that higher earner.

However, if actual beneficial ownership is different from 50/50, married couples and civil partners can notify HMRC of the true split using Form 17(Declaration of beneficial interests in joint property and income). This must be supported by a Declaration of Trust — a legal document — and submitted to HMRC within 60 days of the beneficial interest changing.

For unmarried couples, HMRC taxes each partner on their actual share of beneficial ownership from the outset — so Form 17 is not needed but proper documentation of ownership is still important.

ISA Strategy for Lower Earners

Both partners each have a £20,000 ISA allowanceper year. Income and gains within an ISA are permanently tax-free, regardless of the investor's marginal rate. This makes the ISA wrapper particularly valuable for the lower earner, whose dividends and capital gains would be tax-free inside an ISA regardless of whether they use a GIA.

The key insight for income splitting: if you give cash to a lower-earning spouse or civil partner for them to invest in their own ISA, the investment income and gains that flow from that ISA belong to them. Because an ISA pays out tax-free income, the question of whose tax rate applies is moot — but for taxable investments outside an ISA, directing capital to the lower earner's name has real tax value.

The annual CGT exemption is £3,000 per person in 2026/27, and the dividend allowance is £500. Holding income-producing investments in both names maximises use of these allowances — each partner can realise £3,000 of gains and receive £500 of dividends tax-free each year.

Paying Your Spouse a Salary

If your spouse or civil partner genuinely works in your business, paying them a market-rate salary is a legitimate and effective way to shift income. A salary paid to a spouse is:

• Deductible against your business profits (reducing your taxable income)
• Taxable in your spouse's hands — using their Personal Allowance and basic-rate band
• Subject to PAYE and NI in the normal way

The rules HMRC applies are strict: the work must be real, the rate must be commercially justifiable, and payment must actually be made. If the salary is set at an artificially high rate or the spouse does no meaningful work, HMRC will disallow the deduction.

A spouse earning up to £12,570 from your business pays no income tax (assuming no other income), and both of you will have lower NI bills if their salary is structured carefully. Paying at the NI Secondary Threshold (£5,000 in 2026/27) can give them a qualifying NI year for State Pension purposes at near-zero cost.

Gifting Income-Producing Assets to Your Spouse

Transfers of assets between spouses and civil partners who are living together are exempt from CGT under s58 TCGA 1992 — the receiving spouse takes the asset at the original acquisition cost, not market value. This means you can shift ownership of income-producing assets (rental properties, shareholdings, investment portfolios) without triggering an immediate CGT liability.

Once transferred, the income from those assets is taxed on the receiving spouse. If they pay a lower marginal rate, the tax saving is immediate and ongoing.

The settlements legislation anti-avoidance rules (s620–648 ITTOIA 2005) apply if the arrangement is a "settlement" — broadly, any arrangement under which the settlor retains an interest. Outright gifts of assets with no strings attached are generally outside these rules; arrangements where you give shares that only pay income but have no real capital value (as in Arctic Systems) are at greater risk.

Pension Contributions for the Lower Earner

Tax relief on pension contributions is personal — you cannot make a pension contribution in your spouse's name and receive relief in your own tax return. However, you can give money to your spouse for them to contribute to their own pension. HMRC then grants relief at their marginal rate.

For a non-earner (or someone earning less than £3,600 per year), the maximum gross pension contribution is £3,600 per year even without earnings to match. They contribute £2,880 net; HMRC adds 20% basic relief (£720), making £3,600 in their pension. Over time this can build a meaningful pension pot while also reducing household income tax (because the money gifted to your spouse for pension contributions is no longer in your hands earning taxable interest).

For a basic-rate taxpaying spouse, contributions attract 20% relief. For a higher-rate taxpaying spouse, additional relief can be claimed via Self Assessment. The key principle is that pension relief tracks the contributor, not the source of the cash.

High Income Child Benefit Charge Mitigation

The High Income Child Benefit Charge (HICBC) claws back Child Benefit when either parent's adjusted net income exceeds £60,000 in 2026/27:

Child Benefit rates in 2026/27 are approximately £26.05/wk for the first child and £17.25/wk for additional children(estimated after CPI uprating). For a family with two children that is around £2,236/yr — worth protecting.

The most effective mitigation is pension contributions by the higher earner to reduce their adjusted net income below £60,000. Salary sacrifice pension contributions are particularly efficient because they also reduce NI for both employee and employer. Making a £10,000 gross pension contribution from an income of £70,000 reduces adjusted net income to £60,000, eliminating the HICBC entirely.

Anti-Avoidance: What Doesn't Work

HMRC has several tools to challenge income-splitting arrangements that lack commercial substance:

• Settlements legislation (s620–648 ITTOIA 2005): If you arrange for income to be paid to your spouse but you retain an interest in the arrangement (e.g. you can get the money back, or the gift is revocable), HMRC can treat the income as yours. The classic example is paying a spouse a dividend on shares that have restricted rights — no real capital growth potential, just income rights — when the arrangement was designed primarily for tax.
• Spouse salary without real work:Paying your spouse a salary for performing no services — or at a rate far above market — is disallowed. HMRC can disallow the deduction under the "wholly and exclusively" rule for self-employed people and under employment tax rules more generally.
• GAAR (General Anti-Abuse Rule): Arrangements that are abusive — producing results Parliament clearly did not intend — can be counteracted. In practice GAAR is a last resort; the settlements legislation is more commonly invoked for income splitting.
• Post-Arctic Systems dividend shares: Issuing shares to a spouse with restricted rights (income only, no capital participation) in order to pay them dividends is high-risk following the legislative response to Arctic Systems. Genuine equity participation — shares that participate in growth as well as income — are far safer.

Worked Example