Onshore vs Offshore Investment Bond Tax Calculator

An investment bond is a single-premium life insurance policy used as a tax-efficient investment wrapper. You invest a lump sum, the money grows inside the bond, and you can withdraw up to 5% of the original investment each year without immediate tax (deferred tax). When you encash the bond, any gain above the original investment plus unused 5% allowances is taxed as income.

Onshore bonds (UK-based insurers) pay corporation tax internally at approximately 20% on gains — so gains are received with a 20% 'deemed tax credit'. Higher-rate taxpayers (40%) owe an extra 20% on encashment; basic-rate taxpayers owe nothing further. Offshore bonds (non-UK insurers) grow gross of UK tax inside the bond, but the full gain is taxed on encashment at your marginal rate with no basic-rate credit.

Top-slicing relief spreads the gain across the years the bond was held to calculate the average annual gain. This average gain is added to your income to determine the marginal rate. If the average gain keeps you in the basic rate band, only 20% tax applies (even if the full gain would take you into higher rate). For offshore bonds, this can significantly reduce the tax bill — especially if timed for a low-income year (retirement, sabbatical).

You can withdraw up to 5% of the original investment each year for 20 years without any immediate tax charge. These withdrawals are treated as a return of capital. Any unused allowance can be carried forward. Exceeding the 5% creates an immediate 'chargeable event gain' taxed as income in that year (without top-slicing benefit on the excess).

Offshore bonds are typically more advantageous if: (1) you expect to retire into the basic rate band (encashing at 20% vs onshore which has already paid 20%), (2) you plan to move to a lower-tax jurisdiction before encashing, (3) you are a non-UK domiciled individual, or (4) you want to defer gains to a future low-income year and use top-slicing. They are less advantageous for perpetual higher-rate taxpayers who will encash in a higher-rate year.

Most investment bonds are issued as multiple 'segments' (e.g. 1,000 × £200 segments). You can selectively encash individual segments to control when and how much of the gain you crystallise each year, managing the tax charge. This segmentation strategy (sometimes called 'cluster policies') allows for annual partial encashments up to the basic-rate threshold.

Yes — investment bonds can be written in trust (discretionary or bare trust), allowing the proceeds to pass outside your estate for IHT purposes. A discretionary trust bond can also distribute to different beneficiaries in different tax years, using each beneficiary's personal allowance and basic rate band to minimise tax. Assignment of segments to beneficiaries before encashment is also used.

A chargeable event gain arises when: you fully encash the bond, you take excessive withdrawals (above the 5% annual allowance), the policy matures, you die (if the death benefit exceeds the investment), or you assign the policy. The gain is the value received above the adjusted investment plus unused 5% allowances. It is taxed as income in the year of the event.