Bonus Planning Before 5 April: How High Earners Avoid Accidental Tax Spikes

A bonus paid before 5 April can do more than increase your income tax bill. For high earners, it can also reduce your pension annual allowance through the taper, which may lead to lost tax relief or an annual allowance charge. Planning the timing and structure of the bonus in advance can reduce or avoid that extra cost.

The Invisible Problem: Income Bunching and the Taper

Most high earners understand that earning more means paying more tax. The mechanics feel straightforward: an additional £10,000 of income costs roughly £4,500 in tax and National Insurance if you’re a higher-rate taxpayer. This is uncomfortable but predictable.

But there’s a hidden layer that most people don’t see until too late. For high earners earning between £100,000 and £260,000, an additional £10,000 of income doesn’t just cost £4,500 in direct tax. It can also cost thousands in lost pension relief because of something called the annual allowance taper.

Here’s the core problem: a bonus taken early in the tax year (say, January or February) lands in the same tax year as your salary, and the combined figure determines whether the taper applies. But the taper isn’t calculated until the tax year ends. So you take the bonus, you pay the tax, and then in April you realize that the combined income has triggered a reduction in your pension allowance. By then, it’s often too late to do anything about it.

For some high earners, this cost is entirely invisible. They take a £50,000 bonus in March, pay £22,500 in tax, and think the transaction is complete. They don’t realize that the bonus has also cost them £40,000 of pension relief that would have been available if they’d structured things differently. The total cost isn’t £22,500. It’s £22,500 plus the value of lost pension shelter (which could be worth £10,000 to £20,000 depending on circumstances).

Understanding the Annual Allowance Taper

Let’s start with the basic rule: your pension annual allowance is usually £60,000 per tax year. You can contribute up to £60,000 to a pension and get full tax relief. This applies to nearly everyone.

But if you earn more than £210,000, the taper applies. For every £2 you earn above £210,000, your allowance reduces by £1. So if you earn £230,000, you’re £20,000 above the threshold. Your allowance reduces by £10,000. Your available allowance is therefore £50,000.

If you earn £260,000, you’re £50,000 above the threshold. Your allowance reduces by £25,000. Your available allowance is £35,000.

If you earn £320,000, you’re £110,000 above the threshold. Your allowance would reduce by £55,000, bringing it down to £5,000. It can’t go below £10,000, so your minimum allowance is always £10,000.

This is the basic mechanism. But here’s what makes it problematic for bonus planning: the threshold and the calculation are based on your “adjusted income,” not your actual take-home.

Adjusted Income: The Hidden Calculation

“Adjusted income” is HMRC’s term for the income figure used to calculate whether the taper applies. It includes your salary, your bonus, dividends, rental income, and several other sources. Critically, it includes most, but not all, pension contributions.

For employees, adjusted income is roughly: salary + bonuses + benefits + investment income - pension contributions. The pension contribution reduction applies if the contribution was made via salary sacrifice (before income tax) or via a personal relief pension arrangement (which gets tax relief). Regular employee contributions (post-tax) don’t reduce adjusted income.

For business owners, adjusted income is: profits from the business + salary taken from business + dividends + other income. Employer pension contributions made by the business reduce the taxable profit but are calculated into adjusted income differently than salary sacrifice.

This is where bonus planning gets tactical. If you’re an employee and you take a bonus, and your total adjusted income lands above £210,000, the taper applies. But if you simultaneously make a salary sacrifice pension contribution on that bonus, the contribution reduces your adjusted income, potentially preventing or reducing the taper.

For example: you earn £160,000 salary. You’re expecting a £70,000 bonus. Combined, that’s £230,000, which is £20,000 above the £210,000 threshold. The taper would reduce your allowance by £10,000, leaving you £50,000 of available allowance. But if, before taking the bonus, you enter into a salary sacrifice arrangement and sacrifice £20,000 of the bonus directly into your pension, your adjusted income is now £210,000, the taper doesn’t apply, and you keep your full £60,000 allowance. Plus, you’ve got the £20,000 salary sacrifice contribution reducing your tax. The double benefit is remarkable.

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How Bonuses Create Tax Spikes

Here’s a concrete scenario to make this real. Imagine you’re a senior employee earning £190,000 salary. You’re expecting a £60,000 bonus. Your adjusted income will be £250,000. You’re £40,000 above the £210,000 threshold. The taper reduces your allowance by £20,000. Your available allowance is £40,000.

Now, let’s say you were planning to contribute £50,000 to your pension this year. You have £10,000 of carry-forward from a quiet year last year. So your total available allowance is £50,000. But the taper has reduced your allowance to £40,000. You can’t contribute the full £50,000. You can only contribute £40,000.

What happens to the £10,000 you intended to contribute? It either goes unused (and the allowance is lost), or you can make a “member excess contribution” where you exceed your allowance and pay tax on the excess. Either way, the cost is real.

But here’s the worse scenario: what if you didn’t know about the taper? You contribute £50,000 to your pension as planned. You submit your tax return in January, and HMRC writes to you: you’ve exceeded your annual allowance by £10,000. You now owe a charge on the excess (£4,500 if you’re a higher-rate taxpayer). The bonus, which felt like good news, has become a tax problem.

The psychological experience of this is frustrating. You took a bonus, paid the expected tax, and thought you were done. And then you discover you have an additional tax charge months later because you weren’t aware of the taper.

The Cost of Not Planning: A Worked Example

Let’s work through this carefully with numbers to show the actual cost of income bunching via bonus.

Scenario A: No planning

• Salary: £200,000
• Bonus (March): £80,000
• Total adjusted income: £280,000
• Threshold: £210,000
• Amount over threshold: £70,000
• Taper reduction: £35,000 (£1 for every £2 over threshold)
• Available annual allowance: £25,000 (£60,000 minus £35,000)
• Planned pension contribution: £60,000
• Excess contribution: £35,000
• Tax on excess (at 40%): £14,000

Scenario B: Planned pension contribution before bonus

• Salary: £200,000
• Pension contribution (salary sacrifice): £20,000
• Adjusted income before bonus: £180,000
• Bonus (March): £80,000
• Adjusted income after bonus: £260,000
• Amount over threshold: £50,000
• Taper reduction: £25,000
• Available annual allowance: £35,000
• Second pension contribution (normal): £40,000
• Total contributions: £60,000 (within allowance)
• Tax charge on excess: £0

The difference between scenario A and scenario B is £14,000 in tax charges. And that’s just the direct charge. If you factor in the fact that the £40,000 additional pension contribution in scenario B gets full tax relief (reducing taxable income), the total benefit is even larger.

But here’s the emotional reality: in scenario A, you didn’t plan. You took the bonus, paid tax, and then got a surprise bill. In scenario B, you were deliberate. You made a pension contribution before the bonus, and the outcome was controlled. The peace of mind alone is worth something.

Salary Sacrifice: The Most Tax-Efficient Option

If you’re employed and you’re expecting a bonus, salary sacrifice on the bonus is the most tax-efficient way to manage the taper. Here’s why:

A salary sacrifice pension contribution is made before income tax and National Insurance. So if you sacrifice £20,000 into a pension, your taxable income reduces by £20,000. You avoid income tax (40% for higher earners) and National Insurance (2% for employees, 8% for employers, depending on circumstances). The total tax saving is roughly 42-48%.

But the real power of salary sacrifice is that it reduces your adjusted income before the taper is calculated. So the £20,000 sacrifice doesn’t just give you 40-48% tax relief. It also prevents the taper from triggering or reduces its impact. This is a double benefit that a post-tax contribution doesn’t offer.

The challenge is timing and process. Salary sacrifice on a bonus requires employer cooperation. The employer needs to alter your contract or make a specific arrangement before the bonus is paid. If the bonus is already determined and you’re in February, this might be tight but achievable. If it’s already March, it’s too late.

This is why planning in February matters. Once the bonus amount is confirmed but before it’s paid, there’s a window (usually 2-4 weeks) to arrange salary sacrifice. After the bonus is paid, salary sacrifice isn’t available.

Regular Pension Contributions After the Bonus

If salary sacrifice isn’t possible or if you prefer not to do it, you can make a regular pension contribution after the bonus. This is post-tax, so it doesn’t offer the same tax relief as salary sacrifice. But it can still be valuable.

The key is timing. If you’re going to make a post-tax pension contribution, make it before the bonus is paid. This might sound counterintuitive-how can a contribution made before the bonus affect the taper from the bonus?

The answer is that adjusted income includes certain pension contributions in the calculation. Specifically, relief at source contributions (contributions made post-tax through your pension scheme) are included in the calculation of adjusted income if they’re made before the year-end. So if you make a £10,000 post-tax contribution in February and receive the bonus in March, your adjusted income is calculated with the contribution already factored in, reducing the impact of the bonus.

The benefit is smaller than salary sacrifice (because you’re using post-tax money to fund the contribution), but it’s still valuable. It might reduce the taper impact enough to prevent excess contribution charges.

For Business Owners: Employer Contributions

Business owners have different options than employees because employer pension contributions are made from business profits, not personal salary. Here’s the tactical question: should you make the employer pension contribution before or after determining your bonus?

If you make the employer contribution first, it reduces the taxable profit of the business, which in turn affects what’s available for the bonus. This can be an indirect way of managing the taper-by reducing profit before the bonus is determined.

But this requires coordination with your profit planning. If you’re planning to take a £100,000 bonus and you want to avoid the taper, you could contribute £30,000 to a pension, which reduces the taxable profit to a level where a £100,000 bonus doesn’t trigger the taper. The mathematics works, but it requires advance planning.

The challenge for business owners is that the annual allowance taper is calculated on “adjusted net income,” which for self-employed people includes your profit. Employer contributions reduce profit, but they’re calculated into adjusted income differently than for employees. The calculation is subtle and requires careful review of your specific circumstances.

When Carry-Forward Changes the Maths

Some high earners have unused pension allowance from prior years that they can carry forward. This changes the bonus planning math.

If you have £30,000 of carry-forward available, and you’re expecting a bonus that would normally trigger the taper and reduce your available allowance to £25,000, the carry-forward increases your total available allowance to £55,000. This might be enough to accommodate a contribution that would otherwise exceed your allowance.

But carry-forward is only available if you’ve tracked it and documented it. Many people don’t carry forward consistently, so they don’t have it available when they need it. If you’re planning to manage a large bonus via carry-forward, confirm with your pension provider that they have the carry-forward documentation.

The Emotional Reality of Unplanned Taper

Here’s something that tax planning literature doesn’t always capture: the emotional cost of discovering, in January, that a bonus you took in March has created a tax bill you didn’t expect.

Many high earners experience this. The bonus felt like good news. You paid the immediate tax. You thought you were done. And then you get a letter from your accountant or from HMRC saying you’ve triggered an annual allowance charge. The surprise is frustrating. You feel like you’ve been caught out by a rule you didn’t know about or didn’t think applied to you.

For some people, this is motivation to plan better next year. For others, it’s enough to make them suspicious of bonuses altogether, or to resist pension contributions because they feel like a form of punishment.

The reality is that bonus planning is straightforward once you know the rules. It’s not complicated. It just requires intentional action in February, before the bonus is paid. If you can do that, you eliminate the surprise, and the bonus becomes genuinely positive.

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Building Bonus Planning Into Your Calendar

Here’s a practical system: the moment your bonus structure is announced (usually November or December), mark February as your planning month. In February, confirm with your employer what your bonus will be. Then, based on that amount, determine whether salary sacrifice on the bonus makes sense. If it does, initiate the arrangement. If it doesn’t, plan a separate pension contribution that will be made before or after the bonus as needed.

For business owners, the same principle applies. Once your profit forecast is clear (usually by January), model what bonus you’ll take. Determine whether taking a smaller bonus plus a pension contribution would be more tax-efficient. Then execute the plan by March.

This is not year-end panic planning. This is calm, deliberate planning with months of lead time. And the outcome is certainty: you know what the bonus will cost, and you know the taper won’t surprise you.

Real-World Complication: Multiple Income Sources

For people with salary plus bonuses plus investment income plus dividends, the adjusted income calculation becomes more complex. The bonus isn’t the only thing pushing you above the £210,000 threshold. You might already be there before the bonus.

If you’re earning £220,000 salary, and you’re expecting a £60,000 bonus, your adjusted income is £280,000 before any pension contribution. You’re already £70,000 above the threshold. The taper is already applying. The bonus makes it worse, but you’re not being pushed over the line by the bonus alone.

In these situations, the planning question is whether salary sacrifice or pension contributions will offset enough of the income to prevent the taper from applying to the fullest extent. Sometimes the answer is no-the taper will apply regardless. But understanding this beforehand means you’re not surprised by it.

Working With Your Accountant

Your accountant should be flagging bonus-related taper as a matter of course. If they’re not, it’s worth asking: “Given my income and my bonus structure, should I be concerned about the annual allowance taper? And if so, what’s the most tax-efficient way to manage it?”

A good accountant will model scenarios and give you clear recommendations by February. A reactive accountant will wait until after the year-end and tell you the taper applied.