How cashflow modelling can help married couples and civil partners pay less tax

Off the back of the 2025 Autumn Budget, there’s been nonstop discussion on allowances and thresholds, from capital gains and inheritance tax to child benefit and income tax. But one area that’s not often included in that discussion is that, for some households, all of these allowances can be effectively doubled. 

Because for all the challenges thrown up by our tax system, the transfer of assets (and their associated taxable income) between married spouses and civil partners offers practically unlimited flexibility. It’s potentially a powerful planning tool, but it’s not always easy to understand the best way for eligible couples to hold assets to maximise their tax efficiency over the long term, though of course tax treatment can change, and any plan should be reviewed on a regular basis.

Often, we see tax planning opportunities missed across each tax year, and with increasing tax rates on dividends from April 2026 and property income from April 2027, it’s important to consider your position and understand if you can mitigate tax.

With any discussion around investing, it’s easy to focus solely on gross (before tax) returns. But while returns do have a major bearing on the long-term success of any financial plan, managing tax can arguably make an even bigger difference. The tax strategy should take precedent before you make the call in the investment decision for longevity of funds. 

Consider a share investment worth £500,000 within a general investment account which is generating dividend income of £15,000 (3%) p.a. gross. Depending on the tax band of the asset owner, there can be a huge difference in the net return. From 6 April 2026, estimated:

• For a basic rate taxpayer, the net income would be £13,441.25 (2.69%)
• For a higher rate taxpayer, the net income would be £9,816.25 (1.96%)
• For an additional rate taxpayer, the net income would be £9,294.25 (1.86%)

Same asset, same gross return, vastly different long-term outcome. In reality, the impact is even bigger than illustrated in this simple example. Capital gains, inheritance and dividend income tax are all paid at different rates for different individuals, and this can add up to a staggering variance in outcomes.

The positive side to all this is that the UK’s tax system is designed around individuals, meaning that married couples and civil partners have options when it comes to who pays tax, and how much.  

The ability to transfer assets between married spouses and civil partners without triggering capital gains tax or inheritance tax is one of the most valuable and underused planning opportunities available.

This flexibility allows households to allocate income-producing and growth assets to the partner best placed to hold them from a tax perspective. Over time, this can significantly improve net returns without changing the underlying investment strategy. It also means over each tax year as exemptions, allowances and income changes, you can aim to use these effectively between both partners to reduce overall tax.

For example, if one spouse is a higher or additional rate taxpayer while the other remains within the basic rate band, shifting income-producing assets such as bond funds, dividend-paying equities or buy-to-let property can significantly reduce the household’s overall tax bill. Similarly, crystallising capital gains in the name of the spouse with unused annual exemption or lower marginal rate can reduce or even eliminate capital gains tax.

Asset ownership decisions can also influence exposure to future inheritance tax, the use of personal savings allowances, dividend allowances and even the tapering of child benefit or personal allowances. When considered collectively, aligning asset ownership with each spouse’s tax profile can create a compounding benefit over many years.

Of course, tax should not override investment suitability, risk tolerance or long-term objectives. But where assets are already appropriate for the household, thoughtful structuring of ownership can enhance outcomes without increasing risk.

While these principles sound straightforward, the optimal solution is rarely obvious. What is an appropriate choice today may not continue to be so as assets and incomes rise over time, tax rates change and planning for the shift from accumulation to withdrawal is also important. One spouse may retire earlier than the other, with pension withdrawals, state pension entitlement and future capital gains all interacting in complex ways.  

This is where detailed cashflow modelling becomes essential. By projecting income, expenditure, asset growth and tax liabilities across both lifetimes, planners can test different ownership structures and withdrawal strategies before implementing them. Modelling allows couples to see not just the immediate tax saving, but the cumulative impact on long-term wealth and sustainability with a tax overlay.

For mixed-asset couples holding portfolios across pensions, ISAs, general investment accounts, company structures, investment bonds and property, small adjustments in sequencing and ownership can produce significant differences in lifetime after-tax wealth. In many cases, the question is not simply who should hold an asset, but when income should be taken, which wrapper should be drawn on first, and how that interacts with each spouse’s marginal rate in a given year.

Ultimately, effective planning is about viewing the household as a single economic unit while working within an individual-based tax system. By combining smart structuring with robust cashflow modelling, couples can reduce tax drag and improve the resilience of their long-term financial plan.

For couples whose wealth is split between business relief (BR) qualifying shares and more conventional investment assets, the question of who owns what is rarely neutral. It can materially change how much of the family’s wealth survives two deaths and any intervening sale of the business. 

The difficulty is that the ‘right’ answer depends on timing, behaviour and risk. A structure that looks perfectly efficient today can become expensive if the business is sold, if trading status changes, or if the order of deaths differs from expectations.

The hidden risk in BR-heavy estates

BR is powerful but conditional. If qualifying shares are held at death, they can attract up to 100% relief from inheritance tax dependent upon value and thereafter a 50% discount. For many business owners, that means most of the estate sits outside the IHT net (if under £2.5 million each), at least on paper.

The vulnerability appears when everything passes outright to the surviving spouse. The spouse exemption defers inheritance tax on first death, but it does not preserve BR indefinitely. If the survivor later sells the company, the proceeds cease to qualify. What was once a sheltered asset becomes cash or an investment portfolio fully exposed to IHT on the second death.

For a couple with mixed assets, the interaction is more complex. One spouse may hold most of the BR assets, while the other holds investment property or share-based portfolios. Depending on who dies first, whether a sale occurs, and how long the survivor lives, the ultimate IHT bill can vary dramatically. Looking only at the position on first death misses the bigger picture.

How ownership splits change the outcome

A more balanced ownership structure can create flexibility across capital gains, income and inheritance tax, while also helping to maximise business reliefs. Income can be allocated in a way that makes better use of both spouses’ personal allowances, income tax bands and capital gains can potentially be spread between two individuals, allowing greater use of annual exemptions and lower rate thresholds.

On death, plans can be put in place to route assets or proceeds of a business sale in a way that keeps control in the right hands and manages tax.

This does not mean that equal ownership is always preferable, as concentrated ownership can simplify administration and align with commercial or control considerations. The optimal structure is often a balance between tax efficiency, control and long term flexibility.

In a tax system built around individuals, married couples and civil partners have genuine options in how to navigate it. Careful structuring of ownership can shape how much income tax is paid each year, how capital gains are realised and, ultimately, how much of the estate is exposed to inheritance tax. Over time, those differences can compound into a meaningful gap in outcomes. 

Ultimately, good planning treats the household as one financial unit while working carefully within an individual tax framework. When ownership is structured thoughtfully and reviewed over time, the result is often lower tax drag, greater resilience and a better chance of preserving wealth for the future. Ensuring plans are managed across multiple tax years is vital, as once a year is passed you almost always can’t ‘get back’ any unused allowances or planning options.

To discuss how changes to asset ownership could reduce your tax burden and improve long-term outcomes, speak to your usual Evelyn Partners contact or book an appointment.