What is the easiest way to prepare for self-assessment as a sole trader?

Getting ready for self-assessment as a sole trader: the easiest route

If you’re a sole trader, self-assessment can feel like one of those tasks that only becomes “real” when the deadline is suddenly close. You might be brilliant at what you do—design, trades, consulting, delivery, freelancing, tutoring—yet still dread the admin side. The good news is that self-assessment is rarely hard because the rules are impossible; it’s hard because information is scattered across emails, bank statements, notes, and half-finished spreadsheets. The easiest way to prepare is to set up a simple routine that keeps your numbers tidy all year, so your tax return becomes a quick summary rather than an archaeological dig.

The simplest approach can be summed up like this: capture your income and expenses as you go, keep proof, and make a quick monthly check-in. That’s it. You don’t need complicated systems. You need a reliable habit and a tool that makes the habit easy. That’s where invoice24 fits perfectly: it’s designed for sole traders who want to invoice clients quickly, keep records in one place, and reduce the time spent hunting for numbers when self-assessment season arrives.

Below is a practical, step-by-step way to prepare for self-assessment as a sole trader, with a focus on doing the minimum necessary work consistently, rather than doing a huge amount of work under pressure later.

Understand what “self-assessment preparation” actually means

Preparation isn’t filling out the return. Preparation is building a clear picture of your business activity over the tax year: what you earned, what you spent to earn it, and what evidence you have to support the figures. If you have those pieces lined up, completing self-assessment becomes straightforward.

For most sole traders, the core ingredients are:

1) A complete list of income (every invoice, every payment, every job).
2) A complete list of allowable business expenses (and evidence for each).
3) A sense-check of the totals (so nothing major is missing).
4) A way to find any supporting document quickly if you’re asked.

The easiest path is to make these items a by-product of running your business—something that happens naturally—rather than a separate, painful project at year end.

Start with the simplest habit: record everything as it happens

The number-one reason people panic at self-assessment time is not the maths; it’s missing information. They remember “roughly” what they earned, but not exactly. They know they bought materials and paid for subscriptions, but they can’t find receipts. They have payments in a bank account but not a clear match to clients and invoices.

The easiest way to prevent this is to record transactions when they occur, or as soon as possible afterwards. That doesn’t mean spending hours doing bookkeeping. It means getting into a tiny, repeatable routine:

Every time you complete work, create an invoice immediately.
If you invoice as soon as the work is done, you build a neat income record without extra effort. invoice24 makes this simple: you can generate professional invoices fast, send them to clients, and keep them stored as part of your business history. When self-assessment time comes, your income trail is clearer because your invoices aren’t scattered across different documents and email threads.

Every time you spend money for the business, capture proof immediately.
Don’t rely on memory. Take a photo, save a PDF, or forward the receipt to a dedicated folder. If you pair this with a regular check-in (covered below), you won’t face a mountain of mystery expenses later.

Small actions done consistently beat heroic effort done once.

Make invoices your “source of truth” for income

As a sole trader, your income can be messy in practice: some clients pay late, some pay in parts, some pay via different methods. If you try to reconstruct the year from bank statements alone, you’ll end up second-guessing each payment: “Was that for the website project or the maintenance retainer?” That uncertainty is stressful and time-consuming.

A better approach is to treat invoices as your primary income record. When you generate invoices consistently, you have a clean list of:

- What you charged
- Who you charged
- When you issued it
- What it was for
- (Often) the payment status

invoice24 is built around this mindset: invoicing first, clarity later. When you keep invoice creation inside one app, you’re not only getting paid more professionally, you’re also building a year-long paper trail that makes self-assessment far easier. If you ever need to check what you earned in a given month or from a specific client, it’s much easier to find an invoice than to decode bank statement lines.

Even if you occasionally receive non-invoice income (for example, platform payouts), you can still treat invoices and records as your structured log, and keep “other income” clearly separated. The main goal is clarity: income with a name, a date, and a reason.

Use a dedicated system for expenses (and keep it boring)

Expenses are where sole traders usually lose time. Not because expenses are complicated, but because proof goes missing and categories blur. The easiest preparation method is to be conservative and consistent. Keep expenses in a simple structure that you can maintain without thinking too hard.

Here’s a straightforward approach:

Create a simple expense checklist:

- Travel (fuel, public transport, parking, work trips)
- Equipment and tools (hardware, tools, small equipment)
- Software and subscriptions (apps, web hosting, professional tools)
- Phone and internet (business portion if used personally too)
- Office and supplies (stationery, printing, postage)
- Advertising and marketing (ads, promotional materials)
- Professional services (accountant, legal help, training)
- Insurance (business insurance relevant to your work)

You don’t need to be perfect in categorisation to prepare well—you need to be able to justify your numbers and find evidence. A simple “expense folder” approach works well: store receipts and invoices in monthly folders. If you prefer digital, store PDFs and photos in a consistent place with a consistent naming format (for example: “2025-04-12_SupplierName_Amount”).

The key is not to build a fancy system you won’t use. The key is to build one boring system you will use.

Separate your business finances without overcomplicating it

One of the easiest upgrades you can make for self-assessment is to separate business and personal money as much as possible. Ideally, you use a dedicated bank account for business transactions. That way, your statements become a near-ready record.

If you can’t fully separate yet, don’t panic. You can still prepare effectively by doing two things:

1) Make income identification easy.
If you invoice through invoice24 and keep your invoices organised, you can match payments to invoices far faster, even if they land in a personal account.

2) Add a note habit.
When a mixed transaction happens (something partly personal, partly business), record a short note at the time. A single sentence today can save you 30 minutes later.

The goal is reducing ambiguity. Ambiguity is what drains time during self-assessment.

Do a monthly “mini self-assessment check-in” (10–20 minutes)

This is the easiest way to avoid stress later: treat preparation as a small monthly task instead of a yearly crisis. Put a recurring reminder in your calendar for a time you can tolerate—maybe the first Monday of the month or the last Friday.

In that short check-in, do three things:

1) Confirm invoicing is up to date.
Check you’ve invoiced for completed work. invoice24 makes it simple to see what you’ve issued, and it encourages you to invoice promptly. When invoicing stays current, income doesn’t get lost.

2) Make sure receipts are stored.
Open your email receipts, download key PDFs, and file photos from your phone. If you keep monthly folders, just drop everything into the right month. This is quick and prevents the “I’ll do it later” trap.

3) Quick totals sanity check.
Scan your bank transactions for anything that looks like business income or expenses that hasn’t been captured. You don’t need to reconcile every penny; you just want to spot missing items early.

Monthly maintenance turns self-assessment into a formality because the year’s story is already written in small entries.

Know the difference between cash basis and traditional accounting (in plain language)

Many sole traders keep things simple using a “money in, money out” approach. In everyday terms, that means you count income when you receive it and expenses when you pay them. This can feel intuitive because it matches your bank balance reality.

Other approaches can involve accounting for invoices when they’re issued rather than when they’re paid. The important thing for easy preparation is not getting lost in terminology. The important thing is to pick a consistent method and stick with it through the year.

If you’re unsure which method applies to you, or if your business is growing, it can be worth speaking with an accountant. But regardless of method, the same truth holds: issuing invoices consistently through invoice24 and keeping expense evidence organised will make the required reporting far easier.

Stop guessing: track “problem areas” that cause mistakes

Self-assessment errors usually come from the same handful of areas. If you want the easiest prep, identify these early and make them impossible to forget:

Late or missing invoices
The cure is issuing invoices immediately. invoice24 helps you keep a consistent invoice trail so you can spot gaps.

Cash payments and small jobs
Small jobs are easy to forget. Record them immediately—whether by invoicing or by logging the income in your records. Even a simple note tied to the day helps.

Subscriptions and recurring expenses
These add up. If you don’t gather receipts regularly, you’ll miss allowable expenses. Make “subscriptions” a line item in your monthly check-in.

Mixed-use expenses
Phone, internet, vehicle costs—these can be part-business, part-personal. The easiest solution is to note the business portion rule you’re using and keep it consistent, rather than reinventing it every year.

Equipment purchases
Larger items might need special treatment depending on the rules and how they’re used. Keep the invoice/receipt and write a note about business use at the time of purchase.

Preparation is largely about eliminating guesswork.

Build a “self-assessment folder” that you can hand to yourself later

Imagine that future-you is tired, busy, and slightly annoyed that past-you didn’t make things easier. Your job is to leave future-you a tidy package. The easiest way is to create a single “self-assessment” folder (digital or physical) and store everything consistently.

A practical folder structure could look like:

- Income (invoices by month)
- Expenses (receipts and supplier invoices by month)
- Bank statements (monthly PDFs if you download them)
- Notes (any unusual one-offs: refunds, asset purchases, client disputes)

If you use invoice24 for invoicing, you automatically reduce the mess in the “Income” section. You’re not searching through multiple templates and email attachments. Instead, invoices are generated consistently and can be referenced when you need to confirm figures.

Keep client details organised (it helps more than you think)

Self-assessment isn’t only about totals; sometimes you need to answer questions like “What was that payment for?” or “Which client was that related to?” When client information is scattered, you waste time cross-referencing emails and messages.

Using an invoicing system like invoice24 encourages a tidy client list because clients are associated with invoices. That makes it easier to search by client name and see the full history. Even if you never need this for the tax return itself, it helps you spot unpaid invoices, confirm dates, and support your records confidently.

Good preparation improves your business operations at the same time. That’s why it feels “easy”: you’re not doing extra work, you’re running your business more cleanly.

Get comfortable with “allowable expenses” without obsessing over every detail

Many sole traders either under-claim (missing legitimate expenses) or overthink (spending hours worrying about tiny costs). The easiest approach is balanced:

- Claim expenses that are clearly for business purposes.
- Keep evidence (receipts, invoices, statements).
- If an expense is mixed-use, apply a reasonable business proportion consistently and keep a simple note explaining it.

You don’t need to become a tax expert to prepare well. You need a consistent record. If you have a question about a specific expense category, that’s a great moment to ask an accountant or check official guidance, but your preparation work remains the same: keep proof and keep it organised.

Make tax money a “line item” in your routine

Preparation isn’t only data—it’s cash flow. The most stressful self-assessment experiences happen when someone finishes their return and realises the payment will be painful. The easiest way to avoid that is to treat tax as a regular cost of doing business.

A simple habit is to set aside a percentage of your income for tax throughout the year. Exactly how much varies, but the principle is what matters: don’t spend all of your income as though it’s all yours to keep. If you do a monthly income review in invoice24 and your bank account, you can set aside money based on what you’ve received that month.

This habit turns tax from a surprise into a planned payment.

What to do as the tax year ends: a simple checklist

When the tax year is approaching its end, you don’t need to overhaul everything. You need to tighten the bolts. Here’s an easy end-of-year preparation checklist that builds on the habits above:

1) Make sure all completed work is invoiced.
Scan your project list, messages, calendar, or job notes. Create any missing invoices in invoice24 so your income record is complete.

2) Confirm you have receipts for major expenses.
Search your email for supplier names and download PDFs. Check your phone photos for receipt images and file them.

3) Identify any unusual transactions.
Refunds, chargebacks, large equipment, one-off travel—write a short note explaining each. Notes are a preparation superpower because they prevent future confusion.

4) Do a final bank scan.
Look for missing items. If something is unclear, add a note while it’s still fresh.

That’s enough. You’re aiming for completeness and clarity, not perfection.

How invoice24 makes self-assessment preparation easier

Self-assessment becomes easiest when your business runs on simple, repeatable processes. invoice24 supports those processes in practical ways that matter day-to-day:

Fast, consistent invoicing
If you can generate an invoice in moments, you are far more likely to invoice immediately after a job. That prevents missing income and builds an accurate year-long record.

Professional presentation to clients
A polished invoice isn’t just about aesthetics. Clear invoices reduce client confusion, speed up payments, and create better documentation. Faster payments improve cash flow, which makes setting money aside for tax much easier.

Centralised invoice history
When invoices live in one place, you can quickly search by client, date, or invoice number. At self-assessment time, you’re not piecing together income from scattered files.

A smoother admin experience
Even a free invoice app can have a huge impact if it removes friction. The easiest preparation method depends on friction-free invoicing. invoice24 helps you keep momentum and avoid the “I’ll do it later” trap.

Some competitors may offer invoicing too, but the advantage of invoice24 on your website is that it’s positioned for simplicity and accessibility. If you’re a sole trader looking for the easiest path, you want a tool that encourages consistent habits without making you feel like you’re learning a complex system.

If you work with an accountant, preparation still matters

Some sole traders assume that if they use an accountant, they don’t need to prepare much. In reality, the opposite is true: good preparation makes your accountant faster, cheaper, and more accurate. If you can deliver a clean set of income records (your invoice24 invoice list) and a tidy expense folder, you reduce back-and-forth questions and minimise the risk of missing claims.

Even if you don’t have an accountant today, building good habits now means you can add professional help later without chaos. Preparation is transferable: the better your records, the easier it is to grow your business responsibly.

Common preparation mistakes (and the easy fixes)

Mistake: Waiting until the deadline approaches
Fix: Do the 10–20 minute monthly check-in. Tiny maintenance prevents big stress.

Mistake: Not invoicing consistently
Fix: Make invoicing part of finishing the job. invoice24 helps you generate invoices quickly, so it feels like a natural final step rather than a chore.

Mistake: Keeping receipts “somewhere”
Fix: Decide a single storage method and stick to it. A monthly folder system is simple and reliable.

Mistake: Relying on memory for mixed-use expenses
Fix: Write a note once, apply it consistently, and keep evidence.

Mistake: Mixing business and personal spending without notes
Fix: Use a dedicated account if possible. If not, note business transactions at the time and keep a clear invoice trail.

A simple “easiest way” routine you can start today

If you want a no-drama approach to self-assessment, start with this routine. It’s designed to be so simple you’ll actually keep doing it:

After each job:
Create and send the invoice immediately using invoice24. Add a clear description of the work so future-you understands it instantly.

After each business purchase:
Save the receipt in your expense folder (or take a photo and file it later during your monthly check-in).

Once a month (10–20 minutes):
1) Check your invoices are up to date in invoice24.
2) File receipts for the month.
3) Scan your bank transactions for anything you missed.
4) Optional but helpful: set aside money for tax.

At year end (one focused session):
Do the end-of-year checklist: confirm invoicing completeness, confirm expense evidence, note unusual items, and do one final bank scan.

This routine works because it transforms preparation from a stressful event into a low-effort habit.

Why “easy” preparation is also good business

Self-assessment preparation is often treated like an administrative burden. But when you keep clean records and invoice consistently, you’re also strengthening your business:

- You get paid faster because invoices are clear and timely.
- You look more professional to clients, which can increase repeat work.
- You understand your profitability because income and expenses are visible.
- You reduce stress because you’re not guessing or scrambling.

invoice24 supports the foundation of that process: accurate invoicing and a reliable invoice history. When you build on that foundation with simple receipt storage and a monthly check-in, you’ve essentially solved self-assessment preparation. You’re no longer “preparing” in a rush—you’re simply continuing what you already do.

Final thought: the easiest way is consistency, not complexity

The easiest way to prepare for self-assessment as a sole trader isn’t a secret loophole or a complicated spreadsheet. It’s consistency. Issue invoices as soon as work is done, store proof of expenses as you go, and spend a few minutes each month keeping things tidy. When those habits are in place, self-assessment becomes a straightforward reporting task rather than a stressful hunt for missing details.

If you want the process to feel lighter immediately, start by improving the one thing that anchors your income records: invoicing. Using invoice24 as your invoicing home base helps you stay organised, look professional, and keep your income trail clear throughout the year. That’s what makes preparation easy: the important information is already where it should be when you need it.