What new UK Self Assessment requirements should taxpayers be aware of in the 2024/25 tax year?

Understanding what “new requirements” means for 2024/25

The UK Self Assessment system doesn’t usually change in one dramatic step. Instead, the “new requirements” taxpayers notice in a given tax year tend to fall into a few categories: new rules that start on 6 April, changes to what must be reported (because allowances or thresholds have changed), updated administrative processes from HMRC (for example, penalties and how HMRC collects information), and preparatory steps for larger reforms that are coming soon but are not fully mandatory yet.

The 2024/25 tax year (6 April 2024 to 5 April 2025) sits in a particularly important period. A number of headline changes from recent years begin to bite more visibly in 2024/25 because the amounts involved (such as reduced allowances) make more people fall into reporting, and because some transitional reforms are moving from “special case” into “business as usual”.

This article focuses on Self Assessment requirements and practical implications: who needs to file, what you may need to report that you didn’t before, what records you should keep, and what to do early so you’re not fighting the clock in January.

Key Self Assessment dates for 2024/25 that drive the “requirements”

Even where tax rules change, the Self Assessment timetable remains the backbone of compliance. Missing dates is one of the most common ways otherwise careful taxpayers get penalties.

Tax year: 6 April 2024 to 5 April 2025.

Registration (if newly needing Self Assessment): If 2024/25 is the first year you need to file because you’ve started self-employment, begun receiving untaxed income, or have another reason to enter Self Assessment, you should register as early as possible. In practice, that means registering during 2024/25 or soon after the tax year ends, rather than waiting until the January filing rush.

Paper return deadline: 31 October 2025 (if you submit a paper return).

Online return deadline: 31 January 2026 (for the 2024/25 return).

Payment deadline: 31 January 2026 for any balancing payment due for 2024/25, and for the first “payment on account” for 2025/26 if those rules apply to you. The second payment on account (if due) is normally 31 July 2026.

These dates matter because “new requirements” often translate into “new information you must gather and report by the same deadline”. If you wait until January to work out what’s changed, you’re far more likely to miss something.

Who should double-check whether they need to file in 2024/25

The requirement to file a Self Assessment tax return is triggered by your circumstances, not by preference. Some people file because they must; others choose to file because it is the cleanest way to report and pay. In 2024/25, more taxpayers will find themselves needing to review their position because of the interaction between reduced allowances and increased prevalence of “mixed” income (PAYE plus investments, side income, online sales, or property).

You should review whether you need to file if any of the following apply in 2024/25:

You are self-employed or a partner in a partnership. Self-employment remains a core Self Assessment population. If you started trading in 2024/25 (including freelancing, gig work, or selling goods/services regularly), you should assume you may need to register and file.

You are a landlord or receive property income. Even modest property income can create filing obligations depending on your total income and whether tax is collected automatically. The property allowance can simplify things for very small amounts of property income, but it doesn’t remove the need to keep records.

You have significant investment income. Dividends and capital gains can push people into Self Assessment, particularly as allowances reduce. If you sold shares, cryptoassets, a second property, or other chargeable assets, you may need to report capital gains even if no tax is ultimately due.

You (or your partner) claim Child Benefit and someone in the household has higher income. The High Income Child Benefit Charge (HICBC) can require reporting and paying back some or all of the benefit. Changes to the HICBC thresholds from 2024/25 mean some households will be newly affected and others will have a smaller charge than before, but the need to handle it correctly remains.

You have foreign income or are not UK-domiciled and claim special tax treatment. Cross-border income and residence issues are areas HMRC expects to be reported accurately, and they often require additional pages in the return.

You have untaxed income. This can include side income not taxed at source, certain casual earnings, or income where tax is not fully collected through PAYE. The key point is not whether you think it is “small”, but whether it is reportable and how it interacts with allowances and thresholds.

The practical “new requirement” many people miss: reduced allowances make reporting more likely

In 2024/25, the biggest driver of new Self Assessment filings for employees and retirees is not a brand-new form, but the steady reduction in tax-free allowances that previously kept people out of reporting.

Dividend Allowance: now small enough to pull more people into reporting

The dividend allowance for 2024/25 is significantly lower than it was a few years ago. As the tax-free amount shrinks, more people with share portfolios, investment funds, family company dividends, or dividend-paying ETFs will find that their dividends are either taxable or must at least be considered carefully in the overall picture.

Why this matters for Self Assessment: If you have dividend income beyond the allowance, or if you already file for another reason, you need accurate dividend figures and supporting statements. Even where tax is modest, reporting errors can cause mismatches with HMRC data.

What to do now: Keep your dividend vouchers and platform tax certificates, and maintain a simple tracker of dividend dates and amounts received. For accumulation funds, be alert to “notional distributions” that may be taxable even when not paid out as cash.

Capital Gains Tax annual exempt amount: fewer “no-tax” disposals

For 2024/25, the capital gains annual exempt amount is lower than it has historically been. This means that disposals that previously sat safely under the exemption may now create a taxable gain, or at least require closer calculation.

Why this matters for Self Assessment: You may need to report capital gains if you disposed of assets and the totals exceed certain reporting limits or if tax is due. People who sell shares to rebalance a portfolio, take profits, or move between platforms can unexpectedly create a capital gains reporting requirement.

What to do now: Keep contract notes, acquisition histories, and evidence of costs (including transaction fees). If you sold only part of a holding acquired over time, ensure you can apply the share pooling rules correctly.

High Income Child Benefit Charge: 2024/25 threshold changes and reporting choices

From 2024/25, the income thresholds used to calculate the High Income Child Benefit Charge change, and the tapering works over a wider band. In plain terms, some households that previously faced a charge may face a smaller one, and some that were just above the old threshold may now be outside the charge altogether.

Why this matters for Self Assessment: If you or your partner receives Child Benefit and one partner’s income falls into the HICBC range, you must ensure the charge is handled correctly. Some people pay the charge via Self Assessment; others may be able to pay through an adjustment to their PAYE tax code (where HMRC offers that route and the circumstances fit).

What feels “new” in 2024/25: The changed thresholds mean you should not assume last year’s position is still correct. A household that opted out of Child Benefit payments to avoid the charge may wish to review that decision, especially where National Insurance credits are relevant. Similarly, a household that previously repaid all Child Benefit may find that the charge no longer wipes it out fully.

What to do now: Keep records of Child Benefit received and calculate adjusted net income carefully (especially if you have pension contributions, gift aid donations, or salary sacrifice arrangements that affect the calculation).

Basis Period Reform: 2024/25 is where the new “tax year basis” becomes normal

For many sole traders and partnerships (other than LLPs taxed as companies), one of the most important Self Assessment-related changes is the move to a tax year basis for trading profits. Transitional rules applied around the changeover, and 2024/25 is the first full year where many businesses are simply operating under the new normal.

What this changes in practice: Historically, some businesses were taxed based on accounts ending in a particular accounting period (for example, a year-end of 30 April). Under a tax year basis, the profits taxed align more directly with the tax year (6 April to 5 April). This can require apportioning profits between periods if your accounting date is not aligned to 5 April (or 31 March, which is treated similarly).

Why it matters for Self Assessment requirements: The “requirement” is not a new box to tick; it is the need to calculate taxable profits correctly and retain evidence for apportionments. If your year-end is not 31 March/5 April, you may need more detailed working papers to show how you arrived at the tax-year profit figure.

Practical choices taxpayers are making in 2024/25:

1) Changing accounting date to align with the tax year (commonly 31 March or 5 April) to simplify future returns.

2) Keeping the existing accounting date but accepting an annual requirement to apportion profits and track overlap relief adjustments where relevant.

What to do now: If you are self-employed or in partnership and your year-end is not aligned, speak to your accountant early (or plan your own calculations early). The administrative burden is often the surprise, not the tax rate.

National Insurance changes affecting self-employed returns in 2024/25

Changes to National Insurance Contributions (NICs) can alter what you owe and what you need to consider when filing.

Class 2 NIC reform in 2024/25: From April 2024, the way Class 2 NICs apply to the self-employed changes, including how liability is triggered by profits and how voluntary contributions may be handled for some people. For many taxpayers, this will show up as a different NIC calculation on the return compared with prior years.

Class 4 NIC rates: Class 4 NIC rates and thresholds can change between tax years, and the Self Assessment calculation will reflect the 2024/25 position.

Why this is a “requirement” issue: If your profits are around thresholds, small differences in allowable expenses, timing, or accounting choices can now change not only income tax but also NIC outcomes. That increases the importance of accurate bookkeeping and properly supported expenses.

Administrative changes: penalty points and “compliance by process” expectations

HMRC has been moving towards a points-based approach for certain penalties and a more structured compliance model. While the exact application depends on the obligation (and not every taxpayer will interact with the points system in the same way), the broad direction is clear: repeated lateness or repeated errors are more likely to trigger escalating consequences.

Why this matters for 2024/25 filers: If you are already prone to filing close to the deadline, 2024/25 is a good year to change the habit. HMRC is increasingly data-driven and process-driven, and “I didn’t realise” is not a strong defence when information is available and deadlines are consistent.

What to do now: Aim to complete the return well before January, even if you don’t pay the tax until the deadline. Early filing gives you time to correct mistakes, chase missing documents, and plan cashflow for the payment.

Digital record-keeping and Making Tax Digital: not mandatory yet for 2024/25, but expectations are rising

Many taxpayers have heard “Making Tax Digital for Income Tax Self Assessment” (often shortened to MTD for ITSA) and assumed it already applies. For most individuals in 2024/25, it is not yet mandatory. However, the direction of travel affects what HMRC expects you to be able to produce if asked: cleaner records, clearer audit trails, and faster access to supporting information.

What to treat as a 2024/25 requirement (even before formal mandation):

1) Maintain contemporaneous records. Don’t rely on reconstructing everything from bank statements at year-end.

2) Keep digital copies of key documents. Invoices, receipts, platform statements, and mileage logs are easier to manage when stored systematically.

3) Be consistent. Consistency in categorising income and expenses reduces errors and makes your Self Assessment smoother.

Who benefits most from preparing early: Landlords, sole traders, and anyone with multiple income streams. If MTD later becomes mandatory for you, the transition will be far less stressful if your 2024/25 bookkeeping is already tidy.

Side hustles, online selling, and platform income: the “data visibility” shift

A growing number of taxpayers earn money through online platforms: reselling goods, creating content, providing freelance services, renting assets, or completing gig work. Even where the underlying tax rules are not new, what feels new in 2024/25 is the increasing visibility of platform income and the likelihood that HMRC can match data to tax returns.

Why this matters for Self Assessment requirements: If your income is not fully taxed at source, you may need to register and file. Even if you do not need to file, you must still ensure you declare taxable income through the correct route and keep records that support your position.

Common mistakes that create unexpected filing needs:

1) Treating regular trading as “just selling old stuff” without checking whether activity has the badges of trade.

2) Forgetting that fees, refunds, and chargebacks affect the real income figure and must be accounted for correctly.

3) Mixing personal and business transactions in the same account without a clear method to separate them.

What to do now: Keep platform statements, download transaction histories, and maintain a simple log of costs (postage, packaging, platform fees, software subscriptions, marketing, and any relevant expenses).

Property income: common 2024/25 reporting pressure points

Property remains one of the most frequent causes of Self Assessment complexity. The “new requirement” for many people in 2024/25 is not that property income has suddenly become taxable (it always was), but that reduced allowances and cost-of-living pressures push more people into renting rooms, letting properties, or monetising property in ways they haven’t before.

Areas to watch in 2024/25:

Rent a Room relief vs. property income reporting. If you rent out a room in your main home, special rules may apply. But you still need records, and you need to choose the correct treatment if you file.

Furnished holiday letting and short-term lets. The tax treatment of different types of letting can vary. If you operate short-term lets, keep particularly robust records, as the line between personal use and business use can be scrutinised.

Finance costs and allowable expenses. Ensure you understand what is deductible and what is restricted. Landlord tax calculations can look counterintuitive if you assume everything is a straightforward deduction.

What to do now: Keep a property income and expense spreadsheet (or software ledger), store invoices (repairs, safety certificates, agent fees), and track periods of letting and personal use where relevant.

Foreign income and residency: increased importance of getting the “pages” right

Taxpayers with overseas bank interest, dividends, rental income, or employment income often underestimate the administrative side of Self Assessment: it’s not just the numbers, it’s selecting and completing the correct supplementary pages, and ensuring exchange rates and foreign tax credits (where available) are handled properly.

What feels new in 2024/25: More people have cross-border issues due to remote work, overseas investments via apps, or time spent outside the UK. Even when the tax due is not huge, reporting incorrectly can create prolonged correspondence with HMRC.

What to do now: Keep annual tax certificates from overseas institutions, retain evidence of foreign tax withheld, and maintain a clear travel/work diary if your residence position could be questioned.

Student loans, pensions, and adjustments that change the Self Assessment outcome

For many taxpayers, Self Assessment isn’t only about paying “extra tax”; it is also the mechanism that reconciles adjustments such as student loan repayments and the correct treatment of pension contributions.

Student loan repayments: If you are self-employed or have significant untaxed income, your student loan repayment calculation may be finalised through Self Assessment. This can surprise people who have PAYE deductions but then see additional amounts due because total income is higher than PAYE alone suggested.

Pension contributions and tax relief: Personal pension contributions can extend your basic rate band and reduce adjusted net income for certain charges and allowances. But the relief mechanism depends on how contributions are made (net pay, relief at source, salary sacrifice), and Self Assessment needs the right information in the right boxes.

What to do now: Keep pension statements showing contributions in the tax year, and understand the method used by your scheme. If you are making significant contributions late in the year, keep evidence of the contribution date and amount.

What HMRC expects you to keep: a 2024/25 record-keeping checklist

One of the most practical “requirements” is record-keeping. Even if you file perfectly, you may need to support figures later. For 2024/25, a sensible approach is to assume you should be able to evidence every material number on your return.

For self-employment:

Invoices issued, sales records, bank statements, expense receipts, mileage logs, use-of-home calculations, details of any capital assets purchased, and notes on any private use adjustments.

For property:

Tenancy agreements, rent schedules, agent statements, mortgage interest statements (where relevant to calculations), repair invoices, safety certificates, insurance, and records of any periods not let.

For investments:

Dividend vouchers, platform tax certificates, interest certificates, contract notes for buys and sells, records of reinvested distributions, and calculations supporting any capital gains.

For HICBC and adjusted net income items:

Child Benefit statements, gift aid records, pension contribution confirmations, and any documentation relating to employment benefits or salary sacrifice arrangements.

Common 2024/25 Self Assessment scenarios where people newly fall into filing

Scenario 1: PAYE employee with a growing investment portfolio. A taxpayer who never needed Self Assessment may find that reduced dividend and CGT allowances mean they must now calculate taxable amounts and potentially report them. Even if tax due is small, the compliance requirement can be real.

Scenario 2: New freelance income alongside a salaried job. Someone earning money from consulting, design work, tutoring, or content creation may cross from “occasional” into “trade”, triggering registration and filing.

Scenario 3: Landlord with one property and rising rents. Higher gross rents and changes in expense patterns can increase taxable profit, and if tax is not fully collected through PAYE coding (or if circumstances require), Self Assessment becomes necessary.

Scenario 4: Child Benefit claimant in a changing threshold year. A household that previously repaid all Child Benefit might now repay less, or a household previously just over a threshold might now be outside the charge. Either way, the “requirement” is to revisit the calculation, not assume last year’s answer applies.

How to reduce the risk of penalties in 2024/25

For many taxpayers, penalties feel like something that happens only to people who ignore the system. In reality, penalties often arise from avoidable administrative failures: late filing, late payment, careless errors, or missing information that forces guesses.

Practical steps that work:

1) Create a “tax folder” now. Store all documents for 2024/25 in one place (digital or physical).

2) Do a mid-year check. Around autumn 2024 or early 2025, estimate your likely tax position so the January payment does not come as a shock.

3) Separate business and personal finances. A separate bank account for self-employment or property income can dramatically reduce mistakes.

4) File early even if you pay later. Filing early reduces stress and gives you time to fix issues.

Planning considerations that are not “requirements” but matter in 2024/25

Some issues are not strictly Self Assessment requirements for 2024/25, but they are highly relevant because decisions you make in this year affect future reporting and tax outcomes.

Choosing an accounting date after basis period reform. If you are self-employed, the choice between aligning your year-end to 31 March/5 April versus continuing with a different date can change your annual compliance workload.

Pension contributions and timing. Contributions can influence adjusted net income, which in turn can affect charges and allowances. Timing matters because Self Assessment is based on what happens within the tax year.

Realising capital gains strategically. With a smaller CGT exemption, planning disposals becomes more important. Even basic “bed and ISA” style planning (where appropriate and within rules) can reduce future reporting friction.

A simple action plan for taxpayers filing for 2024/25

Step 1: Identify your triggers. List all income sources in 2024/25: employment, self-employment, property, interest, dividends, capital disposals, benefits/charges, foreign income.

Step 2: Gather documents monthly. Don’t wait until the end of the year. Download platform statements and store receipts as you go.

Step 3: Make an early draft calculation. A rough estimate in late 2024 or early 2025 helps you budget for January 2026 and spot missing records.

Step 4: Decide whether you need professional help. If you have basis period reform complexity, foreign income, significant capital gains, or multiple income streams, an accountant can often save time and reduce risk.

Step 5: File early and pay on time. Aim to file well before 31 January 2026 and plan cashflow for any tax due, including possible payments on account.

Final thoughts: the real 2024/25 “new requirement” is staying proactive

For 2024/25, many of the most important Self Assessment changes are less about a brand-new form and more about the practical consequences of shifting thresholds, reduced allowances, and reforms that make calculations more technical for certain groups (especially the self-employed affected by the tax year basis).

If you take only one lesson into the year, make it this: treat Self Assessment as a year-round process rather than a January event. Keep cleaner records, revisit whether you still need to file based on 2024/25 thresholds and circumstances, and don’t assume that last year’s answer will still be correct. Doing those things turns “new requirements” from an unpleasant surprise into a manageable checklist.