A free guide from Lekhio·Plain English·Checked against GOV.UK·Not affiliated with HMRC
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File your own tax return.
Stop paying for a 15 minute job.

An accountant charges a few hundred pounds to fill in a form that, once your records are in order, takes about 15 minutes. Here is exactly how to do it yourself, in plain English, for free.

The honest bit: the 15 minutes is the form. The hard part was always the year of receipts behind it. That is the part Lekhio does for you, so the form really is 15 minutes.

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First, which applies to you?

The way you file depends on your turnover, the total you take before expenses.

You file the normal Self Assessment return, once a year

This is most sole traders today. One return, due online by 31 January, covering the tax year that ran 6 April to 5 April. Follow the seven steps below and you are done. Keep your records tidy through the year and it is quick.

From April 2026 you use Making Tax Digital

If your turnover is £50,000 or more, you must keep digital records and send four short quarterly updates plus a final declaration, instead of one return. The first quarter, 6 April to 5 July 2026, is due by 7 August 2026.

This is exactly what Lekhio is built for. It keeps the digital records and prepares each update, so the change is no extra work for you. The seven steps below still help you understand the whole picture.

The walkthrough, click through it

Exactly what to do at each step, with a look at the screen you will see.

GOV.UK
Self Assessment
Your Unique Taxpayer Reference
1234 567 890
Posted to you in 2 to 3 weeks.
Step 1 of 7

Register and get your UTR

First time only. You tell HMRC you have started working for yourself.

1On GOV.UK, search 'register for Self Assessment' and choose self employed.
2Enter your details and the date you started trading.
3HMRC posts your 10 digit UTR within 2 to 3 weeks.
4Set up your Government Gateway user ID and password. You need these every year.
💡 Registered before? Skip this. Just have your UTR and Gateway login ready.
Before you start
✓UTR and Gateway login
✓National Insurance number
✓Total income
✓Total expenses
✓Other income (P60)
Step 2 of 7

Gather your numbers

Five things, in front of you before you start.

1Your UTR and Government Gateway login.
2Your National Insurance number.
3Your total income for 6 April 2025 to 5 April 2026.
4Your total allowable expenses, ideally split by category.
5Any other income: a job (P60), interest, or dividends.
💡 With Lekhio, your income and expense totals are already added up and split by category.
HMRC sign in
Government Gateway user ID
1357924680
Password
••••••••
Sign in
✓ Tax year 2025 to 2026
Step 3 of 7

Log in and open the return

Everything happens on the official HMRC website.

1Sign in to the HMRC Self Assessment service with your Gateway login.
2Start the return for the 2025/26 tax year.
3Add the self employment section. This is the SA103.
4The system picks the short or full version from your turnover.
💡 Turnover under £90,000 uses the short pages, SA103S. It is quicker.
SA103 Self employment
Turnover
£38,400
Allowable expenses
£9,250
Net profit, worked out for you: £29,150
Step 4 of 7

Fill in your self employment pages

The heart of it. Two figures, plus the detail.

1Enter your turnover: everything you invoiced or were paid, before expenses.
2Enter your allowable expenses, by category: materials, travel, phone, insurance.
3Income under £1,000? Use the £1,000 trading allowance instead of real expenses.
4Buying big tools or equipment? Claim them as capital allowances.
💡 Split expenses into categories, do not lump them into one box. It is cleaner if HMRC asks.
Your tax, worked out
Profit£29,150
Less personal allowance-£12,570
Income tax, 20%£3,316
Class 4 NI, 6%£995
Your bill£4,311
Step 5 of 7

Let HMRC do the maths

You do not work out the tax. The return does.

1Add any other income, like a PAYE job from your P60.
2The return applies your £12,570 personal allowance automatically.
3It works out your Income Tax and your Class 4 National Insurance.
4It shows your final bill, and any payments on account.
💡 Class 2 NI changed recently. Most people no longer pay it separately but still build their state pension.
Submit your return
Submit return
✓
Submission received
Reference IRMARK 9F2A7C
Step 6 of 7

Check, submit, save the proof

Slow down here for one minute.

1Read the calculation. Check it matches your own records.
2Press submit. HMRC confirms on screen straight away.
3Save or screenshot the confirmation and your submission reference.
4That is your return filed. Done.
💡 Filed early? You still do not pay until 31 January. It just means no last minute panic.
Pay by 31 January
JAN
31
Set aside as you go
£4,311 ready
Roughly 30% of profit, saved already.
Step 7 of 7

Pay what you owe by 31 January

The deadline that matters.

1Pay your bill by 31 January, online, by bank transfer, or through your tax code.
2If your bill is over £1,000, you also make payments on account towards next year.
3That is half by 31 January and half by 31 July.
4Set aside roughly 30% of your profit as you go.
💡 Lekhio gives you a running set aside figure, so the money is always there when the bill lands.

You make the actual submission on the official HMRC website. We are not HMRC and we never submit on your behalf.

What can you claim? Pick your trade

Every trade claims the basics. Tap yours to see the extras that are specific to you. The rule is always the same, a cost must be wholly and exclusively for the business.

Every trade can claim

✓Materials and stock used on jobs
✓Tools and equipment, often the full cost in the year you buy them
✓Vehicle running costs, or the flat mileage rate
✓Protective clothing and safety gear, boots, gloves, hi vis, hard hats
✓Phone and broadband, the business share
✓Insurance, public liability, tools, professional indemnity
✓Trade body and certification fees
✓A share of home costs for quotes and admin
✓Accounting or bookkeeping software, including Lekhio
✓Business bank charges
✓Advertising and a website
✓Training that maintains your trade skills

Electricians, on top of the basics

✓Cable, fittings and consumer units
✓Test equipment and its calibration
✓18th Edition and scheme fees (NICEIC, NAPIT)
✓PAT testing kit
✓Van racking and storage

Plumbers, on top of the basics

✓Pipe, fittings, copper and plastic stock
✓Leak detection and pressure testing kit
✓Blow torch and consumables
✓WaterSafe or scheme membership
✓Van racking

Builders, on top of the basics

✓Aggregates, cement, timber and fixings
✓Plant hire
✓Skip and waste disposal
✓Scaffold hire
✓Site PPE

Construction trade: if you work under the CIS, tax is deducted from your pay at source. You still file a return, and that tax comes off your final bill or is refunded. Keep your CIS statements.

Plasterers, on top of the basics

✓Plaster, beading and boards
✓Mixing equipment and stilts
✓Dust sheets
✓Tower or scaffold hire
✓PPE and masks

Construction trade: if you work under the CIS, tax is deducted from your pay at source. You still file a return, and that tax comes off your final bill or is refunded. Keep your CIS statements.

Roofers, on top of the basics

✓Tiles, felt, battens and lead
✓Harnesses and fall arrest gear
✓Scaffold and tower hire
✓Ladders and roof ladders
✓PPE

Construction trade: if you work under the CIS, tax is deducted from your pay at source. You still file a return, and that tax comes off your final bill or is refunded. Keep your CIS statements.

Joiners, on top of the basics

✓Timber and sheet materials
✓Ironmongery and fixings
✓Power tools and blades
✓Dust extraction
✓Workshop costs if you have one

Construction trade: if you work under the CIS, tax is deducted from your pay at source. You still file a return, and that tax comes off your final bill or is refunded. Keep your CIS statements.

Decorators, on top of the basics

✓Paint, fillers and sundries
✓Brushes, rollers and trays
✓Dust sheets
✓Sanding and spray equipment
✓Access towers

Tilers, on top of the basics

✓Tiles, adhesive and grout
✓Trims and levelling systems
✓Cutters and mixing kit
✓Knee pads and PPE
✓Tower or access hire

Gas engineers, on top of the basics

✓Parts and fittings
✓Flue gas analyser and its calibration
✓Gas Safe registration
✓Tools, manuals and standards
✓Van racking

Scaffolders, on top of the basics

✓Tube, fittings and boards
✓Harnesses and PPE
✓Transport of materials
✓CISRS card and training
✓Vehicle and trailer costs

Construction trade: if you work under the CIS, tax is deducted from your pay at source. You still file a return, and that tax comes off your final bill or is refunded. Keep your CIS statements.

Groundworkers, on top of the basics

✓Aggregates, concrete and drainage materials
✓Plant and digger hire
✓Fuel for plant
✓Setting out kit
✓Site welfare and PPE

Construction trade: if you work under the CIS, tax is deducted from your pay at source. You still file a return, and that tax comes off your final bill or is refunded. Keep your CIS statements.

Landscapers, on top of the basics

✓Plants, turf and aggregates
✓Paving and materials
✓Mowers and machinery
✓Green waste and tip fees
✓Fuel and machine servicing

Hairdressers & barbers, on top of the basics

✓Products, colour and supplies
✓Scissors, clippers and tools
✓Chair or booth rent
✓Gowns, towels and PPE
✓Insurance and training

Cleaners, on top of the basics

✓Cleaning products and supplies
✓Vacuums and equipment
✓Mileage between jobs
✓Gloves and PPE
✓Insurance and DBS checks

Drivers & couriers, on top of the basics

✓Fuel or the mileage rate
✓Vehicle running and servicing
✓Licensing and badges
✓Phone and delivery apps
✓Insurance

Beauticians & nail techs, on top of the basics

✓Products and consumables
✓Kit, lamps and tools
✓Couch or room hire
✓PPE and sanitiser
✓Insurance and training

Photographers, on top of the basics

✓Cameras, lenses and gear
✓Editing software and storage
✓Studio or location hire
✓Travel to shoots
✓Website and insurance

Personal trainers, on top of the basics

✓Equipment and weights
✓Gym or studio hire
✓App and music subscriptions
✓Insurance and qualifications
✓Branded kit

Tutors, on top of the basics

✓Books and learning resources
✓Printing and materials
✓Room or online platform hire
✓Travel to students
✓DBS and memberships

Designers & freelancers, on top of the basics

✓Software subscriptions
✓Laptop and equipment
✓Website and hosting
✓Home office or co-working
✓Training and stock assets

The deadlines for 2025/26

The tax year ran 6 April 2025 to 5 April 2026. Miss the 31 January and it is an automatic £100 penalty, even if you owe nothing. So we remind you.

5 Oct 2026
Register for Self Assessment, if it is your first return for 2025/26.
31 Oct 2026
Paper tax return deadline, if you file on paper.
30 Dec 2026
File online if you want a small bill collected through your tax code.
31 Jan 2027
File online and pay what you owe. The big one.
31 Jul 2027
Second payment on account, if you make them.

The once a year return is changing

Making Tax Digital is the biggest shake up to Self Assessment in years. From April 2026, if you turn over more than £50,000 you keep digital records and send four short updates a year instead of one return. It reaches £30,000 in 2027 and £20,000 in 2028, so it is coming for nearly every sole trader.

You do not need to panic. If your records build themselves as you go, the quarterly bit is already done. That is the whole point of Lekhio.

Every question, answered

The things people actually ask before filing for the first time.

Do I really not need an accountant?
For a straightforward sole trader, no. The online return works out the tax for you, and once your records are in order the form takes about 15 minutes. If your affairs are complex, an accountant can still be worth it. The choice is yours, and now you can make it from an informed place.
What is a UTR?
Your Unique Taxpayer Reference. A 10 digit number HMRC gives you when you register for Self Assessment. You need it every time you file, so keep it somewhere safe.
I have a job and do this on the side. Do I still file?
Yes. Tax is taken from your job through PAYE, but your self employed income is not, so you report it on a Self Assessment return. You add your job from your P60, and HMRC works out the combined picture.
What if I earned under £1,000?
If your total self employed income for the year is under £1,000 you may not need to report it, thanks to the trading allowance. If you earned more but had tiny costs, you can claim the flat £1,000 instead of real expenses.
What about National Insurance?
Self employed people pay Class 4 National Insurance on their profits, and the online return calculates it automatically. You do not work it out yourself. Class 2 changed recently, most people no longer pay it separately but still build up their state pension entitlement.
What are payments on account?
If your tax bill is over £1,000, HMRC asks you to pay towards next year in advance, half on 31 January and half on 31 July. It catches first timers out, so set money aside. Lekhio gives you a running set aside figure.
When do I need to charge VAT?
Only once your turnover passes £90,000 in a 12 month period. Below that you do not register for VAT unless you choose to. Most sole traders are well under it.
What records do I need to keep?
Your sales and income, your business expenses with receipts, and your mileage if you claim it. Keep them for at least 5 years after the 31 January deadline. Lekhio stores all of this for you as you go.
What if I miss the deadline?
You get an automatic £100 penalty the day after, even if you owe no tax. After 3 months daily penalties start, and interest is charged on tax paid late. That is exactly why we send the reminder to your WhatsApp.
I am in construction and tax is taken off my pay. What then?
That is the Construction Industry Scheme, CIS. Contractors deduct tax from your pay at source. You still file a return, and that deducted tax comes off your final bill or is refunded to you. Keep your CIS statements.
Can I claim my van and fuel?
Yes. Either claim a share of your actual running costs, or use the flat mileage rate, which is 45p a mile for the first 10,000 business miles for 2025/26. That rate rises to 55p from April 2026, so it will be higher on next year’s records.
What is Making Tax Digital and does it affect me?
It is the biggest change to Self Assessment in years. From April 2026, if your turnover is over £50,000 you must keep digital records and send four short updates a year instead of one return. It reaches £30,000 turnover in 2027 and £20,000 in 2028, so it is coming for nearly everyone. Lekhio keeps the digital records both routes now expect.

Make the 15 minutes actually 15 minutes

Keep your records with Lekhio through the year. Snap a receipt, leave a voice note, or just text it. When the deadline comes, your numbers are already added up and ready, and we send the reminder to your WhatsApp. Your first 14 days are free.

Start free for 14 days