Self Assessment 2025/26: What documents should you start gathering now?
If completing your Self Assessment usually ends up being a last-minute rush, this year could be different. Although you have until 31 January 2027 to submit your online 2025/26 Self Assessment tax return, starting early makes life much easier. You’ll have more time to gather your paperwork, check your figures and deal with any missing information before the deadline approaches.
That’s true whether you’re self-employed, a landlord, a company director or have additional income to declare. Good record keeping has also become increasingly important with the introduction of Making Tax Digital (MTD) for Income Tax. Those taxpayers in scope (landlords and the self-employed with annual income of over £50,000 for the tax year 2024/25) are now required to keep digital records, making it essential to stay organised throughout the year.
In this guide, we’ll explain which documents you should be collecting now, what HMRC expects, and how early preparation can help make tax season much less stressful.
Why prepare early?
Getting ahead now means you can:
- Collect all your documents in one place.
- Find or replace anything that’s missing without rushing.
- Have time to check you’re not missing valuable tax reliefs.
- Have a better idea of your tax position before payment deadlines.
- Avoid the panic that often comes with the January deadline.
A little preparation now can save you a lot of time, stress and unnecessary hassle when it’s time to file your tax return.
Documents you should start gathering
The exact documents you need will depend on your circumstances, but most Self Assessment taxpayers should begin collecting the following.
Employment income
If you’ve been employed during the tax year, gather:
- P60
- P45 (if you changed jobs)
- P11D (if you received taxable benefits)
- Details of any employment expenses you may be able to claim
These documents help ensure your employment income and tax already paid are reported correctly.
Self-employed income
If you’ve been employed during the tax year, gather:
- P60
- P45 (if you changed jobs)
- P11D (if you received taxable benefits)
- Details of any employment expenses you may be able to claim
These documents help ensure your employment income and tax already paid are reported correctly.
Rental income
Landlords should prepare:
- Rental income received
- Letting agent statements
- Mortgage interest statements
- Repairs and maintenance costs
- Insurance documents
- Service charges
- Ground rent
- Safety certificate costs
- Other allowable property expenses
If you own more than one property, keeping separate records for each property can make preparing your return much easier.
Again, if you’re within the scope of MTD for Income Tax, you’ll also need to have maintained digital records using compatible software.
Investment income
Don’t forget income that may not arrive through your main bank account.
This may include:
- Bank interest
- Dividend statements
- Investment income
- Savings income
- Bond income where applicable
Many taxpayers overlook smaller amounts that still need to be declared.
Pension income
If you’ve started drawing a pension, collect:
- Pension statements
- Annual pension summaries
- Details of any lump sum payments
This helps ensure your taxable pension income is reported accurately.
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Benefits and other income
Depending on your circumstances, you may also need information relating to:
- State benefits that are taxable
- Student loan repayments
- High Income Child Benefit Charge where applicable
- Foreign income
- Trust income
If you’re unsure whether something needs to be declared, it’s always worth asking your accountant rather than making assumptions.
Capital gains information
If you’ve sold assets during the tax year, keep records of:
- Purchase price
- Sale price
- Purchase and selling costs
- Dates of acquisition and disposal
This may apply to shares, second properties and other chargeable assets.
Pension contributions and Gift Aid
These can often affect your tax calculation.
Keep records of:
- Personal pension contributions
- Gift Aid donations to charities
Having complete records helps ensure you’re claiming any available tax relief.
Business expenses
One of the biggest reasons taxpayers pay more tax than necessary is missing allowable expenses.
Depending on your business, this may include:
- Office costs
- Telephone and internet
- Professional subscriptions
- Insurance
- Travel expenses
- Mileage records
- Marketing costs
- Software subscriptions
- Equipment purchases
- Training that qualifies as an allowable business expense
Good record keeping throughout the year makes these much easier to identify.
Is Making Tax Digital something you need to think about?
Making Tax Digital (MTD) for Income Tax is already changing how many sole traders and landlords manage their tax affairs.
If your total income from self-employment and property was more than £50,000 in your 2024/25 Self Assessment tax return, you’ll need to follow the MTD rules from 6 April 2026.
The scheme will then expand to people with qualifying income of more than £30,000 from April 2027 and more than £20,000 from April 2028.
It’s worth remembering that these income limits are based on your gross income before expenses are deducted, not your profit. If you’re unsure whether MTD applies to you, it’s a good idea to check now rather than wait until you’re contacted by HMRC.
If you’re affected, you’ll need to:
- Keep digital business records.
- Use HMRC compatible software.
- Submit quarterly updates.
- Complete a final annual submission to finalise your tax position.
Importantly, HMRC advises that you should continue keeping your original supporting records, such as invoices and bank statements, even when maintaining digital records.
For the January 2027 self assessment deadline, you will complete a standard self assessment return for the 2025/26 tax year, even though you have started reporting on a quarterly basis. The first MTD for IT annual return will occur in January 2028 and be done through the MTD for IT software.
Create one place for everything
Rather than searching through emails and paperwork next January, create a dedicated folder now.
You could organise it into sections such as:
- Employment
- Self-employment
- Property
- Investments
- Pensions
- Expenses
- Donations
If you already use cloud accounting software, uploading receipts regularly can make year-end preparation significantly easier.
Self Assessment doesn't have to be stressful
Every year we help people who are self-employed, landlords, company directors and individuals with additional income complete their tax returns without the panic that often comes in January.
We’ll tell you exactly what information you need, check everything carefully and make sure your return is submitted correctly. If Making Tax Digital applies to you, we’ll also help you understand the new requirements and keep you on the right track.
The earlier you start, the easier the whole process becomes, giving you plenty of time to deal with any questions before the deadline gets close.
If you’d like some expert support with your Self Assessment, get in touch today. We’ll help you get organised early and make filing your return much less stressful.
Author
Mukund is a founding member of the Affinity Associates Group and has been with the practice for nearly 40 years. After completing his degree in Accounting and Finance, he went on to qualify with both ACCA and ICAEW in 1991. Over the years, he’s built deep expertise in consultancy, tax, business development, and corporate group structures. Mukund is known for helping clients make sense of complex financial challenges and turning them into opportunities for sustainable growth.
