How are UK Self Assessment thresholds and reporting rules changing in the 2024/25 tax year?

What the 2024/25 tax year means for Self Assessment

The UK Self Assessment system is often described as “the tax return,” but in practice it is a set of registration thresholds, reporting triggers, deadlines, and calculation rules that determine who needs to file, what must be reported, and when the tax is due. The 2024/25 tax year (running from 6 April 2024 to 5 April 2025) brings several practical changes that affect both whether you need to complete a return and how you report certain types of income and gains.

Some changes are headline-grabbing—like removing the automatic requirement for many high earners on PAYE to file just because their income is above a certain figure—while others are more technical but can have a bigger impact on the numbers you report, such as basis period reform for sole traders and partnerships. On top of that, allowances and thresholds that shape what you owe (and sometimes whether you need to file at all) continue to shift, and HMRC is steadily redesigning the way certain charges can be paid without a return.

This article explains the most important Self Assessment threshold and reporting-rule changes that apply for 2024/25, how they compare to the previous year, and what to look out for when you are deciding whether you need to register, file, or simply keep better records.

Key dates and deadlines to keep in mind

Although this article focuses on the 2024/25 tax year, most people engage with the system later—often months after 5 April 2025. Understanding the timetable helps you see how rule changes bite in real life.

If you need to file a Self Assessment return for 2024/25, the usual deadlines apply: paper returns are due by 31 October 2025, online returns by 31 January 2026, and the balancing payment for 2024/25 is typically due by 31 January 2026. Payments on account may also be due on 31 January 2026 and 31 July 2026, depending on your circumstances. If you are newly required to file, you normally need to register by 5 October 2025 for 2024/25.

These dates matter because some “who needs to file” rules connect to whether a charge can be collected through PAYE or whether HMRC expects Self Assessment, and because late filing or late payment penalties can quickly become the dominant cost of getting it wrong.

The big headline change: high earners on PAYE are no longer pulled into Self Assessment by income alone

One of the most significant threshold changes for 2024/25 is the removal of the automatic Self Assessment filing trigger that applied to many people with high PAYE income. In earlier years, people with employment income above a specified level were often required to file a return even when their tax affairs were otherwise straightforward and their income was already taxed at source through PAYE.

For 2024/25, that “income-only” trigger has been removed. This does not mean high earners never file; it means they are not required to file solely because their PAYE income exceeds a particular threshold. If you have other reasons to file—such as untaxed income, significant investment income that cannot be fully taxed at source, capital gains that require reporting, self-employment profits, partnership income, or certain charges—then Self Assessment can still be necessary regardless of your salary level.

In practical terms, this change is designed to reduce the number of people who are drawn into Self Assessment when HMRC can collect the right tax through PAYE and other reporting systems. If you are employed and your financial life is otherwise “PAYE-clean,” you may find that 2024/25 is the first year in which you are not automatically expected to complete a return purely because your income is high.

What hasn’t changed: the common triggers that still require a 2024/25 return

Even with fewer high earners automatically filing, the core Self Assessment triggers remain. You typically still need a return if you are self-employed (as a sole trader) and your gross income from self-employment is above the relevant de minimis level, if you are a partner in a partnership, or if you have taxable income that isn’t fully dealt with through PAYE or withholding.

In real life, the most common continuing triggers include:

• Self-employment (including side hustles) where gross trading income goes beyond the small-income threshold or where you want to claim certain expenses and reliefs.

• Rental income where you have taxable property profits or need to claim costs and reliefs that require a return.

• Capital gains that require reporting (for example, where gains exceed allowances or where specific reporting rules apply).

• Certain charges and tax adjustments, such as where HMRC cannot easily collect the right amount through PAYE, or where you are claiming reliefs that need to be declared formally.

• More complex investment situations (for example, foreign income, some forms of savings/investment income, or income requiring additional pages).

The removal of the “high income alone” trigger is therefore best seen as a narrowing of the net, not a transformation of the whole system.

Basis period reform becomes “real” for 2024/25 Self Assessment reporting

For sole traders and partnerships, 2024/25 is the first tax year in which the new tax year basis applies as the standard method of assessing trading profits. This follows the transitional arrangements that applied in 2023/24 for many businesses that did not already use a 31 March or 5 April accounting date.

Historically, many businesses were taxed on the profits of an accounting year ending in the tax year (for example, a business with a 31 December year end could be taxed on the year ending 31 December 2024 for the 2024/25 tax year). Under the new approach, the tax year basis aligns trading profits with the tax year itself (6 April to 5 April), regardless of the accounting date.

This creates a reporting change: instead of simply lifting a set of “accounts profits” into the return, some businesses must apportion profits between periods to match the tax year. In other words, your accounting period might still run to (say) 30 September, but your taxable profit for 2024/25 must reflect profits earned between 6 April 2024 and 5 April 2025.

For businesses that already prepared accounts to 31 March or 5 April, the practical impact is often minimal. For everyone else, the impact can be significant: more calculations, more estimates if final accounts are not ready by filing time, and more attention to overlap relief and transitional profit spreading (where relevant).

Transitional profits and overlap relief: how they can affect what you report

If you were affected by the transitional year rules in 2023/24, you may still feel the impact in 2024/25 because transitional profits can often be spread over multiple years. This is less about a “new threshold” and more about a reporting rule that changes the shape and timing of taxable profits.

Under transitional arrangements, some businesses faced a one-off “catch-up” effect where more than 12 months’ worth of profits were brought into charge. To soften the blow, spreading provisions can allow transitional profits (after overlap relief) to be taxed over a period of years rather than all at once. If you are in that position, the 2024/25 return may include a portion of those transitional profits as an additional amount on top of the profit you would otherwise report for the year.

This matters because it can push you into higher tax bands, affect your payments on account, and interact with allowances that are sensitive to income. It can also change whether you need to file at all, because once you are in Self Assessment for trading income, you are generally in the system until HMRC agrees you can leave it (for example, if you cease trading).

Dividend and capital gains allowance reductions: not “Self Assessment thresholds,” but they change who ends up needing to report

Even when filing triggers stay the same, changes to allowances can pull more people into Self Assessment in practice because more people end up with a tax liability or a reporting requirement. In 2024/25, two key allowances are lower than in prior years: the dividend allowance and the annual exempt amount for Capital Gains Tax.

The dividend allowance for 2024/25 is much smaller than it was historically. For people with share portfolios, director/shareholder dividends from owner-managed companies, or dividend-paying funds outside tax shelters, this increases the chance that dividends are taxable and need to be declared. Some dividends can be taxed through adjustments to the tax code, but many people still use Self Assessment to finalise the position, particularly if they have other income streams or their dividends are large enough to make coding-out impractical.

The Capital Gains Tax annual exempt amount is also substantially reduced compared with previous years. That means more disposals result in taxable gains, and more people need to work out gains, losses, and reporting positions even when their total gains are not enormous in headline terms. While not every capital gain automatically forces a Self Assessment return, reduced allowances increase the number of cases where a return becomes the simplest or expected route to declare gains and pay the tax.

High Income Child Benefit Charge: changed thresholds and shifting reporting options

The High Income Child Benefit Charge (HICBC) is a classic example of a rule that affects both liability and reporting. For years, the charge started when an individual’s adjusted net income exceeded a specific threshold and increased gradually until it effectively clawed back all Child Benefit at the upper end of the band.

From 6 April 2024, the income threshold at which the charge starts is higher, and the taper works differently. That change means some families who previously had to repay some or all of their Child Benefit no longer do, and others repay less. In terms of Self Assessment, this can reduce the number of people who need to register solely due to HICBC, particularly where that was their only reason to file.

At the same time, HMRC has been moving towards enabling more people to deal with HICBC without completing a full return, for example by collecting the charge through PAYE in appropriate cases. The direction of travel is clear: if your only issue is HICBC and your employment income is already taxed through PAYE, HMRC increasingly aims to provide routes that reduce the need for Self Assessment. However, whether you can use those routes depends on timing and your wider tax position. If you have other Self Assessment triggers, you may still need to file and calculate the charge through the return.

Side income, online selling, and the £1,000 allowances: clearer expectations, stronger nudge activity

Many people first encounter Self Assessment because they start earning “extra” income outside employment: freelancing, creating content, selling goods, offering services, driving/delivery work, short-term letting, or other casual trading. A key point is that the UK has small-income allowances (notably the trading allowance and property allowance) that can simplify reporting in low-value cases, but they do not eliminate your responsibility to understand whether you should notify HMRC.

The widely used de minimis concept in this area is the £1,000 level: if your gross trading income is no more than £1,000 in the tax year, the trading allowance can often mean you have nothing to pay and nothing to report (depending on your circumstances). Similarly, small amounts of property income can sometimes be dealt with via the property allowance. But if you exceed the relevant threshold, or if you want to claim actual expenses instead of using the allowance, you may need Self Assessment.

In 2024/25, the underlying allowances are not the “new story” so much as enforcement and data. HMRC has more third-party information than ever, and is increasingly proactive in nudging taxpayers whose activity looks inconsistent with what has been declared. If you are earning through platforms, taking card payments, receiving regular transfers that look like business income, or generating rental income, you should assume HMRC has a growing ability to cross-check. The practical rule change is therefore less about the letter of the threshold and more about the reality that “small casual income” is less likely to remain invisible.

Property income reporting: the continuing split between simple cases and return-worthy cases

Property income remains one of the most common reasons people need Self Assessment, and in 2024/25 the core structure remains familiar: rental profits are generally taxable, allowable expenses reduce the taxable profit, and losses can often be carried forward against future property profits.

Where reporting rules feel like they are changing is in the growing range of property situations that fall outside “one straightforward rental property.” Examples include furnished holiday letting rules (subject to the rules applicable for the year), jointly owned property with unequal beneficial interests, rental income with significant finance and improvement costs that need correct treatment, and situations where income is partly taxable and partly covered by reliefs (such as letting a room in your own home under specific conditions).

If you have modest property income and HMRC can adjust your tax code to collect the right amount, you might not need a full return in some cases. But if your property profits are higher, your situation is complex, you have multiple income sources, or you need to claim losses or reliefs, Self Assessment remains the normal route. For 2024/25, the practical tip is to focus on records: dates, amounts, invoices, the difference between repairs and improvements, and evidence for apportionments where you have mixed personal and rental use.

National Insurance changes for the self-employed: more than a calculation tweak

For self-employed people, Self Assessment is not just about income tax; it is also where National Insurance contributions (NICs) are calculated and paid. In 2024/25 there are important changes to how the self-employed are charged, particularly around Class 2 NICs and the rates that apply under Class 4.

Even if you view these as “just” NIC changes, they can affect reporting decisions. For example, people with very low self-employment profits sometimes choose to file (or not file) based on whether they want NIC credits or need to pay voluntary contributions. Others may find that changes to the structure of contributions affect their payments on account and the difference between what they set aside and what they ultimately owe.

The broader point is that 2024/25 reinforces the need to treat Self Assessment as a combined income tax and NICs exercise if you are self-employed. When you compare year-on-year results, make sure you are comparing like with like: a lower “tax bill” might be offset by a different NIC outcome, or vice versa.

Capital gains reporting: lower allowances mean more calculations, and more people reaching for a return

When the annual exempt amount is high, many taxpayers never need to calculate gains precisely. As the allowance shrinks, more people must track acquisition costs, incidental costs of disposal, and the interaction of gains and losses across the year. This is particularly true if you sell investments in multiple tranches, move between funds, or have holdings in different platforms.

For 2024/25, the key practical change is behavioural: more people will find themselves needing to work out whether they owe Capital Gains Tax and, if they do, how to report it. In some cases, there are standalone reporting routes for specific types of gains (for example, certain UK property disposals), but a Self Assessment return is often the cleanest way to consolidate all gains, losses, and relief claims for the year.

If you are close to the boundary, keep an eye on two different concepts that are easy to confuse: the total proceeds from disposals (what you sold things for) and the total gains (profit after deducting costs and reliefs). Which matters depends on the rule you are dealing with, and the distinction can affect whether you must report even if you end up owing little or no tax.

Putting it together: who is most likely to notice changes in 2024/25?

Although the Self Assessment framework applies to everyone equally, the 2024/25 changes land most clearly for certain groups:

• Employed high earners whose only income is PAYE salary and who were previously filing mainly because their income exceeded a threshold. They may now be able to stop filing if there is no other trigger.

• Sole traders and partners whose accounting date is not aligned with the tax year. They face the biggest practical reporting changes because of the tax year basis and the knock-on effects of transitional rules.

• Investors with dividends or gains that were previously covered by larger allowances. Reduced allowances increase the chance of a tax liability and therefore the need to report or reconcile through Self Assessment.

• Families affected by the High Income Child Benefit Charge, especially those near the new threshold. Some will fall out of the charge, others will pay less, and more may be able to deal with it without a full return depending on their overall situation.

• People earning side income through platforms, freelancing, reselling, or short-term letting. The thresholds may be familiar, but the expectation of correct reporting is stronger and the margin for “I didn’t realise” is thinner.

A practical checklist for 2024/25: decide early, file calmly

If you want to avoid panic in January, the best approach is to decide early whether 2024/25 is a Self Assessment year for you. A practical checklist looks like this:

1) List every income source you had between 6 April 2024 and 5 April 2025: employment, self-employment, rental income, interest, dividends, foreign income, casual income, and any one-off payments.

2) Identify what was taxed at source through PAYE or withholding and what was not.

3) Check whether any specific charges apply to you (such as HICBC) and whether you can settle them through PAYE or need Self Assessment.

4) If you are self-employed or in a partnership, confirm how the tax year basis affects your profit figure for the year and whether you need apportionments or estimates.

5) If you sold assets, work out whether you need to calculate and report capital gains and whether a return is the easiest way to do so.

6) If you are newly within Self Assessment, note the registration deadline and do not leave it until the autumn of 2025—delays in setting up accounts and getting access credentials can create avoidable stress.