UK Self-Employed First Year Setup 2026/27: Complete Checklist

Setting up as a sole trader in the UK has 7 must-do steps - some immediate, some by hard deadlines through the first year. Missing any of them costs penalties.

Step 1: Register for Self Assessment

Deadline: 5 October following the tax year you started trading.

Register at gov.uk/register-for-self-assessment. You'll need:

• National Insurance number
• Personal details (name, date of birth, address)
• Business description + start date
• Tax reference (will be assigned)

HMRC sends a 10-digit Unique Taxpayer Reference (UTR) by post within 10 working days. Keep it - you need it for every Self Assessment submission and tax payment.

Late registration penalty: up to 100% of the tax due if missed by more than 12 months.

Step 2: Decide on a business name

Sole traders can trade under their own name (no registration needed) OR a business name. If using a business name:

• Cannot include "Ltd", "Limited", "PLC" or similar
• Cannot be offensive, contain restricted words, or imply incorrect status
• Must be on all invoices, letters, websites

No requirement to register a sole trader business name with Companies House - that's for Ltd companies only.

Step 3: Open a business bank account (optional but recommended)

Not legally required for sole traders, but separating business from personal transactions makes the year-end accounting drastically simpler. Most UK challenger banks (Starling Business, Tide, Monzo Business, Revolut Business) offer free sole-trader accounts with mobile app + categorisation.

Direct benefits:

• Easier tracking of allowable expenses
• Lower risk of personal spending leaking into your tax return
• Some lenders require it for business loans / overdrafts

Step 4: Set up bookkeeping

Required for Self Assessment. Two options:

Spreadsheet (free): list every income and expense by date. Suitable for fewer than 100 transactions/year. Will not work for MTD ITSA from April 2026 if turnover exceeds £50,000.

Bookkeeping software: FreeAgent (free with NatWest/Mettle), Xero, QuickBooks, Sage, FreshBooks, Crunch, ANNA. £5-£35/month typical. Required if you're in scope for MTD ITSA (see Step 7).

Minimum information to record per transaction:

• Date
• Amount
• Description / category
• VAT (if VAT-registered)
• Counterparty name
• Reference number (invoice number for income, receipt number for expenses)

Step 5: Understand allowable expenses

You can deduct from gross income to compute taxable profit:

Always allowable:

• Office supplies, stationery
• Travel (55p/mile up to 10,000 business miles, 25p above from 6 April 2026 - first AMAP uplift since 2011; rail/bus/parking)
• Phone + broadband (proportion for business use)
• Professional indemnity insurance
• Public liability insurance
• Trade subscriptions + memberships
• Accountancy fees
• Business banking fees

Allowable with proportion:

• Home office: HMRC simplified flat rate £10/£18/£26/month based on hours, OR actual costs proportioned by room + time
• Vehicle running costs: actual costs × business miles / total miles (alternative to AMAP mileage method)
• Phone: business call proportion as % of total (HMRC Business Income Manual BIM47820 for sole-trader phone expenses)

Never allowable:

• Entertainment of clients (since 1988)
• Fines (parking, speeding)
• Donations to political parties
• Most clothing (HMRC BIM37910, applying Mallalieu v Drummond [1983] - exception: uniform with permanent logo, PPE)

Step 6: Track Class 2 + Class 4 NI

Class 2 NI 2026/27 - £3.65/week. Post April-2024 reform: if profits exceed the £7,105 Small Profits Threshold (2026/27 rate) you receive State Pension and Maternity Allowance qualifying years automatically without paying. Voluntary Class 2 is the route if your profits are BELOW £7,105 - paying £189.80/year secures the qualifying year that would otherwise be lost.

Class 4 NI 2026/27 - automatic on profits via Self Assessment:

• £0 - £12,570: 0%
• £12,570 - £50,270: 6%
• £50,270+: 2%

Step 7: Prepare for MTD ITSA

Making Tax Digital for Income Tax Self Assessment - mandatory from:

• April 2026 for sole traders / landlords with gross income > £50,000
• April 2027 for £30,000+
• April 2028 for £20,000+

If in scope, you must:

• Keep digital business records
• Submit quarterly updates to HMRC (4 quarterly deadlines: 7 August / 7 November / 7 February / 7 May, plus the final declaration by 31 January)
• Use HMRC-approved bridging software or accounting software

Free/low-cost MTD ITSA software: FreeAgent (free via NatWest), QuickBooks (£8/mo), Sage Accounting (£12/mo), Crunch (free).

Year-end timeline (first year)

For someone starting in May 2026:

• By 5 October 2027: Register for Self Assessment
• By 31 January 2028: First Self Assessment return due (2026/27 tax year) + tax payment
• By 31 January 2028: First Payment on Account 1 (if tax due > £1,000) - 50% of estimated 2027/28 tax
• By 31 July 2028: Payment on Account 2 (next 50%)
• By 31 January 2029: Second Self Assessment return + balancing payment + first POA for 2028/29

Payments on Account: if your first year's tax is below £1,000 OR more than 80% of your tax is already collected via PAYE, you may be exempt - HMRC will tell you in your tax calculation.

Common first-year mistakes

1. Missing the 5 October registration deadline - automatic penalty.
2. Forgetting to budget for tax - first SA bill includes 2026/27 tax PLUS first POA = often 150% of one year's tax in a single January payment. Set aside 25-35% of monthly profit.
3. Treating all car costs as deductible - mileage method or actual costs, not both. Mixed personal/business mileage requires apportionment.
4. Mixing personal + business cards - creates VAT-inspection nightmare if you ever register.
5. Not paying voluntary Class 2 NI when profit is below the £7,105 SPT - costs ~£190 but secures a State Pension qualifying year (worth £358/year for life). Post-April-2024 reform: above the SPT the qualifying year is automatic without payment.
6. No professional indemnity insurance - depending on trade, can be £100k+ liability for one mistake.

Tools

• Self-employed calculator - Class 2 + Class 4 + Income Tax for any profit level
• Salary calculator - if you also have PAYE income to combine
• Salary projection - model multi-year profit trajectory
• Statutory pay timeline - if you're considering Maternity Allowance via voluntary Class 2

Not tax advice. For complex setups (mixed self-employment + PAYE, multiple businesses, partnership, partial Ltd-co structure) engage a chartered accountant in your first year.