What do I need for my first Self Assessment?

You need your UTR (Unique Taxpayer Reference), National Insurance number, Government Gateway login, records of all income received, details of business expenses with receipts, and P60/P45 if you're also employed.

When is my first Self Assessment due?

Your first Self Assessment is due by 31 January following the end of the tax year. If you started self-employment between April 2024 and April 2025 (tax year 2024/25), your first return is due by 31 January 2026.

How much tax will I pay on my first Self Assessment?

Tax depends on your profit after expenses. You pay 0% on the first £12,570 (Personal Allowance), 20% on £12,571-£50,270, 40% on £50,271-£125,140, and 45% above that. You also pay National Insurance on self-employment profits.

Can I do my first Self Assessment myself?

Yes. Most people can file their own first Self Assessment using HMRC's online service or tax software like TaxFolio. It's straightforward if you have organised records of income and expenses.

First Time Filing Self Assessment: Beginner's Complete Guide

Filing your first Self Assessment tax return can feel overwhelming, but it's simpler than most people expect. This beginner's guide walks you through everything from registration to submission, helping you file your first return confidently and correctly by the 31 January deadline.

First-Time Self Assessment Timeline

If this is your first year filing, here's your timeline:

| When | What to Do | |------|------------| | As soon as you start earning | Begin keeping records of income and expenses | | Within first few months | Register for Self Assessment with HMRC | | By 5 October | Registration deadline (following tax year end) | | 6 April – 5 April | The tax year you're reporting on | | By 31 January | File your return and pay tax owed |

Example: You started freelancing in June 2024. The tax year is 2024/25 (6 April 2024 – 5 April 2025). Register by 5 October 2025. File and pay by 31 January 2026.

Step 1: Register for Self Assessment

Before you can file, you need a Unique Taxpayer Reference (UTR).

How to Register

Go to gov.uk/register-for-self-assessment
Create a Government Gateway account (if you don't have one)
Select your registration type (self-employed, landlord, etc.)
Provide your personal and business details
Submit the registration

What Happens Next

HMRC posts your UTR within 10 working days
Your UTR is a 10-digit number (e.g., 1234567890)
Keep it safe—you'll use it for all tax matters

Learn more: Self Assessment Registration Guide

Step 2: Understand What You're Reporting

Self Assessment reports your income and expenses for the tax year (6 April to 5 April).

Income to Report

| Income Type | What to Include | |-------------|-----------------| | Self-employment | All money received for work (invoiced and cash) | | Rental income | Rent from tenants, Airbnb, etc. | | Employment | Already taxed via PAYE—but still report if filing | | Savings interest | Above Personal Savings Allowance | | Dividends | Above Dividend Allowance (£500) | | Other income | Anything not taxed at source |

Expenses to Deduct

Expenses reduce your taxable profit. Only claim costs that are "wholly and exclusively" for business:

| Category | Examples | |----------|----------| | Office costs | Software, stationery, phone (business %) | | Travel | Mileage (45p/mile), public transport, parking | | Professional fees | Accountant, legal advice, subscriptions | | Marketing | Website, advertising, business cards | | Equipment | Computer, tools (or capital allowances) | | Home office | Simplified expenses (£10-26/month) |

Learn more: Tax Deductions Guide

Step 3: Keep Records Throughout the Year

Good records make filing easy. Poor records make it stressful.

What Records to Keep

| Record Type | Keep For | |-------------|----------| | Sales invoices | All income | | Bank statements | Proof of transactions | | Expense receipts | Every business purchase | | Mileage log | Business travel | | Contracts | Client agreements |

How Long to Keep Records

Keep all records for 6 years after the tax year. HMRC can enquire within this period.

Record-Keeping Tips for Beginners

Separate bank account — Don't mix business and personal
Photograph receipts — Paper fades; digital doesn't
Categorise as you go — Don't leave it until January
Use software — Makes tracking automatic

Step 4: Calculate Your Profit

Your tax is based on profit, not income:

Profit = Total Income − Allowable Expenses

Example Calculation

First-Year Freelancer:

| Item | Amount | |------|--------| | Total income received | £28,000 | | Office costs | £600 | | Software subscriptions | £480 | | Travel (mileage) | £1,200 | | Home office (simplified) | £216 | | Professional fees | £300 | | Total expenses | £2,796 | | Taxable profit | £25,204 |

Step 5: Understand Your Tax Bill

Income Tax

| Band | Taxable Amount | Rate | |------|----------------|------| | Personal Allowance | £0 – £12,570 | 0% | | Basic Rate | £12,571 – £50,270 | 20% | | Higher Rate | £50,271 – £125,140 | 40% | | Additional Rate | Over £125,140 | 45% |

National Insurance (Self-Employed)

| Type | Rate | When | |------|------|------| | Class 2 | £3.45/week (£179.40/year) | Profits over £6,725 | | Class 4 | 6% | Profits £12,570 – £50,270 | | Class 4 | 2% | Profits over £50,270 |

First-Year Tax Calculation Example

Using the £25,204 profit from above:

Income Tax: | Band | Amount | Tax | |------|--------|-----| | Personal Allowance | £12,570 | £0 | | Basic Rate (£25,204 − £12,570) | £12,634 | £2,526.80 | | Total Income Tax | | £2,526.80 |

National Insurance: | Type | Calculation | Amount | |------|-------------|--------| | Class 2 | £179.40 | £179.40 | | Class 4 | 6% × (£25,204 − £12,570) | £758.04 | | Total NI | | £937.44 |

Total First-Year Tax: £3,464.24 Effective Tax Rate: 13.7%

Step 6: File Your Return

Option A: HMRC Online (Free)

Sign in at gov.uk/self-assessment-tax-returns
Complete the SA100 form section by section
Add supplementary pages (SA103 for self-employment, SA105 for property)
Review your tax calculation
Submit

Pros: Free Cons: Manual data entry, no bank connection, basic interface

Option B: Tax Software (Recommended)

Connect your bank account
Software imports and categorises transactions
Review and adjust figures
Software calculates your tax
Submit directly to HMRC

Pros: Faster, fewer errors, bank integration, real-time calculations Cons: Annual cost (typically £70-150/year)

TaxFolio is HMRC-recognised software from £69.99/year.

Learn more: How to File Self Assessment

Step 7: Pay Your Tax

Payment Deadline

Pay by 31 January following the tax year.

For 2024/25 tax year: Pay by 31 January 2026.

How to Pay

| Method | Notes | |--------|-------| | Online banking | Use your UTR + "K" as reference | | Debit card | Via HMRC website | | Direct Debit | Set up for future payments | | Bank transfer | BACS or Faster Payments |

Payment on Account (Maybe)

If your tax bill exceeds £1,000, you may need to make payments on account—advance payments towards next year's bill:

31 January: 50% of this year's bill (as advance for next year)
31 July: Another 50%

This can be a surprise for first-timers. Budget accordingly.

Common First-Time Mistakes

1. Missing the Deadline

The 31 January deadline is firm. Miss it and you face:

£100 automatic penalty
£10/day after 3 months (up to £900)
Further penalties at 6 and 12 months

Solution: File early—even in April if you have the records.

2. Forgetting to Register

You need a UTR before you can file. If you register late, you can't file on time.

Solution: Register as soon as you start earning taxable income.

3. Not Claiming Legitimate Expenses

Many first-timers under-claim expenses, paying more tax than necessary.

Solution: Review common expense categories. If it's genuinely for business, claim it.

4. Wrong Tax Year

The tax year runs 6 April to 5 April, not January to December.

Solution: Income received on 1 March 2025 is in 2024/25. Income received on 10 April 2025 is in 2025/26.

5. Mixing Business and Personal

Using one bank account for everything makes record-keeping difficult.

Solution: Open a dedicated business bank account—even a free one.

6. Not Keeping Receipts

Without receipts, you can't prove expenses if HMRC enquires.

Solution: Photograph receipts immediately. Store digitally.

7. Forgetting About Payments on Account

Your first filing may also require payment on account for next year.

Solution: Budget for 150% of your expected tax bill for the first payment.

First-Time Checklist

Before You Start

[ ] Registered for Self Assessment
[ ] Received UTR from HMRC
[ ] Set up Government Gateway online access
[ ] Gathered all income records
[ ] Organised expense receipts
[ ] Got P60/P45 (if also employed)

During Filing

[ ] Reporting correct tax year (6 April – 5 April)
[ ] Included all income sources
[ ] Claimed all legitimate expenses
[ ] Checked calculations match your records
[ ] Reviewed tax calculation before submitting

After Filing

[ ] Saved submission confirmation
[ ] Noted payment amount and deadline
[ ] Set up payment method
[ ] Saved records for 6 years
[ ] Marked next year's deadlines in calendar

Special Situations for First-Timers

Part-Year Self-Employment

If you started partway through the year:

Report only income from when you started
Claim expenses from when you started
Still get full Personal Allowance (not pro-rated)

Example: Started freelancing 1 September 2024. Report income and expenses from September 2024 – 5 April 2025 only.

Self-Employed AND Employed

If you have a day job plus freelance work:

Employment income (PAYE) goes in the employment section
Self-employment income goes in SA103
Both combine for your total taxable income
You may be pushed into a higher tax bracket

Small Amount of Income

If your self-employment income is under £1,000:

The Trading Allowance means you don't need to file for self-employment
But you may still need to file for other reasons

Made a Loss

If expenses exceed income (a loss):

Report the loss
It can offset other income this year, or
Carry forward to reduce future profits

Losses are valuable—don't forget to claim them.

What to Expect: Your First Filing Experience

Time Required

| Situation | Approximate Time | |-----------|-----------------| | Simple self-employment, organised records | 1-2 hours | | Simple self-employment, messy records | 3-5 hours | | Multiple income sources | 2-4 hours | | Using software with bank connection | 30-60 minutes |