How can pension contributions reduce your adjusted net income for HMRC purposes?

Why do pensions matter near the £100,000 threshold?

If you are close to the £100,000 threshold, pension contributions can be one of the most important things to review. Done properly, they may reduce your adjusted net income, improve tax efficiency, and help protect valuable childcare support.

This is where many people get caught out: earning a little more does not always mean you keep more. Around the £100,000 mark, the way pension contributions are made can affect the income figure HMRC uses for key thresholds.

HMRC uses adjusted net income for a number of important tax rules. If adjusted net income goes over £100,000, your Personal Allowance starts to reduce. For childcare support, expected adjusted net income can also affect whether you qualify for schemes such as Tax-Free Childcare and Free Childcare for Working Parents.

That is why pensions can be so powerful in planning terms. In the right circumstances, they do not just help you save for later. They may also reduce the income figure HMRC looks at now.

How can pension contributions reduce adjusted net income?

The detail matters here. HMRC guidance explains that adjusted net income is not just your salary. It starts with your taxable income and then takes off certain reliefs, including some pension contributions.

In broad terms, pension contributions may help in three common ways:

• Pension contributions paid gross can reduce the figure used in the adjusted net income calculation.
• If your pension provider gives basic-rate relief automatically, HMRC says you should take off the grossed-up amount when working out adjusted net income.
• Salary sacrifice for pensions can reduce taxable pay, which can in turn reduce adjusted net income, depending on the arrangement and tax year.

The important point is that the route matters. Two people putting the same amount into a pension can see the effect show up differently depending on whether the contribution is made through payroll, relief at source, or salary sacrifice.

What are the three main ways pension contributions are made?

1. Net pay arrangements

Under a net pay arrangement, pension contributions are taken from pay before Income Tax is worked out. This means tax relief is given up front through payroll. For many employees, that lowers the taxable pay shown for tax purposes straight away.

This can make net pay arrangements particularly helpful if you are trying to understand how much income is actually being brought into the adjusted net income calculation.

2. Relief at source

With relief at source, you pay a net contribution and the pension provider claims basic-rate tax relief from HMRC and adds it to your pension. If you are a higher-rate or additional-rate taxpayer, you may need to claim extra tax relief separately.

For adjusted net income purposes, HMRC guidance says you take off the grossed-up amount, not just what left your bank account. That is a key point and one of the reasons relief at source can be more valuable near thresholds than people first realise.

3. Salary sacrifice

Salary sacrifice works differently. Instead of making a pension contribution from your pay, you agree to reduce salary and your employer pays more into your pension instead. Because your contractual pay is lower, this can reduce taxable pay and may reduce adjusted net income too.

This can be especially attractive because it may also affect National Insurance, although the exact outcome depends on the arrangement and the rules in force for the relevant tax year. It is also subject to employer availability and cannot reduce pay below minimum wage rules where those apply.

What are the practical benefits of increasing pension contributions near the threshold?

If you are close to the £100,000 line, increasing pension contributions may help in more than one way at the same time.

• It may reduce adjusted net income and therefore help preserve or restore access to certain childcare support, depending on your circumstances.
• It may reduce the effect of the Personal Allowance taper if you would otherwise be over £100,000.
• It moves money into long-term savings instead of losing more of it to tax.
• With the right pension setup, it may also improve the overall efficiency of how you take pay and benefits from work.

A simple example: if someone expects adjusted net income of around £102,000 to £105,000, a pension contribution might reduce that figure. But it is never just about the headline salary. Other income, benefits, bonuses, and the method of contribution all affect the result.

What many people overlook: the mistake is often assuming that pension contributions only matter for retirement. In practice, they can also be a planning tool for the current tax year.

They can be especially relevant if you receive bonuses, have benefits in kind, or are expecting income to move above a threshold temporarily. In those situations, reviewing pension contributions before the end of the tax year can be more valuable than waiting until after the year has closed.

What limits and checks should you know about?

Pensions are helpful, but they are not unlimited. Tax relief is still subject to HMRC rules.

• You normally get tax relief on private pension contributions up to 100% of your annual earnings, subject to the rules for the type of scheme you are in.
• The annual allowance is currently £60,000 for most people, although some people have a lower allowance and others may be able to carry forward unused allowance from the previous three tax years.
• If you have flexibly accessed a pension, different limits may apply.
• If you have a high income, the tapered annual allowance may apply.

This is why a good blog can explain the principle, but a personal check is still important before making bigger contributions.

What is the smart next step if you are close to £100,000?

If you think you may be close to £100,000 adjusted net income, a useful review would include:

• checking your expected adjusted net income for the tax year
• understanding how your current pension scheme gives tax relief
• reviewing whether extra pension contributions could change the position
• checking annual allowance and any carry forward before paying in more
• using HMRC guidance or professional advice if your situation is complex

The bottom line: pension contributions are not just about retirement. Near key HMRC thresholds, they can also be one of the most effective ways to improve tax efficiency and potentially reduce the income figure used for childcare and Personal Allowance rules.

The right approach depends on your income, your pension type, how contributions are made, and what other income you have. But if you are close to the threshold, pensions are one of the first areas worth reviewing carefully.