How to Submit Tax Return to HMRC Online
Complete Step-by-Step Guide for 2026
Learn exactly how to register, file, submit, and pay your HMRC Self Assessment tax return online without confusion. This complete UK tax filing guide explains every step clearly for freelancers, landlords, sole traders, company directors, and self-employed individuals.
Let’s be honest — hearing the words “tax return” makes most people instantly stressed. Between HMRC rules, deadlines, paperwork, and confusing terminology, it can feel overwhelming before you even begin.
The good news is that filing your tax return online is much easier once you understand the process properly. HMRC’s online system guides you through each section step-by-step, and once you complete it for the first time, future tax returns become significantly easier.
This detailed guide explains everything you need to know — from registering for Self Assessment to submitting your final return and paying your tax bill correctly.
🔗 Official HMRC Links:
• Log in to your HMRC online account →
Do You Need to Submit a Tax Return?
Not everyone in the UK needs to file a Self Assessment tax return. If you only earn income through PAYE employment, HMRC usually handles your taxes automatically.
You usually need to file a tax return if:
- You’re self-employed and earned over £1,000
- You received rental income from property
- Your income exceeded £100,000
- You received foreign income
- You earned untaxed income
- You sold shares, crypto, or property with capital gains
- You are a business partner or company director
- You need to claim tax reliefs or expenses
Related guides: Do I Need to File a Self Assessment Tax Return UK? → | Do PAYE Employees Need Self Assessment? → | Do Landlords Need to File a Tax Return UK? →
Important HMRC Tax Return Deadlines
| Deadline | Description |
|---|---|
| 5 April | End of UK tax year |
| 5 October | Register for Self Assessment (if this is your first year) |
| 31 October | Paper tax return deadline |
| 31 January | Online tax return & payment deadline |
| 31 July | Second payment on account (if applicable) |
Warning: Missing the 31 January deadline results in an automatic £100 penalty from HMRC, even if you owe no tax. Read more: What Happens If You Don’t File a Tax Return UK? →
Step 1: Register for Self Assessment
If this is your first time filing a tax return, you must register with HMRC before you can submit anything online.
After registration, HMRC sends your:
- Unique Taxpayer Reference (UTR) — a permanent 10-digit number used to identify you with HMRC
- Government Gateway credentials — to access your online account
Your UTR is essential for all future tax returns and HMRC correspondence.
Full guide: How to Register for Self Assessment UK →
Step 2: Create Your Government Gateway Account
HMRC online services operate through the Government Gateway system.
You’ll need:
- UTR Number
- National Insurance Number
- Email Address
- Phone Number
Once your account is created, enable two-factor authentication for secure login access. This protects your tax information from unauthorised access.
Step 3: Gather Your Documents
Before starting your tax return, collect all required financial documents. Having everything organised beforehand makes the process much smoother.
📄 Income Records
- P60 and P45 forms
- Self-employment income records
- Rental income statements
- Dividend statements
- Bank interest records
- Foreign income documents
💰 Expense Records
- Travel expenses
- Office supplies
- Marketing costs
- Software subscriptions
- Professional fees
- Equipment purchases
Complete guide: What Documents Do You Need for Tax Return UK? →
Step 4: Log Into HMRC and Start Your Return
Log in using your Government Gateway credentials and navigate to:
- Self Assessment
- Complete Tax Return
HMRC will guide you through:
- Tailoring your return to your specific situation
- Entering income details from each source
- Claiming allowable expenses
- Reviewing automatic calculations
- Submitting the return
Employment Income Section
If you worked as an employee, enter details from your P60:
- Total pay
- Total tax deducted
- National Insurance contributions
If you had multiple employers, each employer must be entered separately. This ensures HMRC has a complete picture of your employment income.
Self-Employment Income (SA103)
This section applies to freelancers, contractors, and sole traders.
Allowable Business Expenses include:
- Office costs
- Business travel
- Equipment purchases
- Advertising and marketing
- Phone and internet bills
- Accountant fees
Important: HMRC only allows genuine business expenses. Personal expenses cannot be claimed against your business income.
Specialist help: Self-employed tax return services →
Rental Income Section
Landlords must declare:
- Total rent received
- Repairs and maintenance costs
- Insurance costs
- Letting agent fees
- Mortgage interest (20% tax credit under Section 24 rules)
For landlords: Property and landlords tax services → | Do Landlords Need to File a Tax Return UK? →
Savings Interest and Dividends
Declare all:
- Bank interest
- Investment dividends
- Shareholder payments
HMRC automatically applies relevant allowances including the Personal Savings Allowance (£1,000 for basic rate, £500 for higher rate) and Dividend Allowance (£500 for 2024/25).
For investors: Investors and capital gains services →
Capital Gains Tax (CGT)
You may need to report gains from:
- Property sales (including buy-to-let)
- Shares and investments
- Cryptocurrency
- Valuable assets over £6,000
CGT rules can become complicated quickly, especially for crypto and property transactions. The Annual Exempt Amount for 2024/25 is just £3,000 — down significantly from previous years.
Review Your HMRC Tax Calculation
After entering your information, HMRC calculates:
- Your taxable income
- Income tax due
- National Insurance contributions
- Payments on account for next year
- Refunds or additional tax owed
Important: If your tax bill exceeds £1,000, HMRC may require payments on account toward next year’s tax bill. These are due on 31 January and 31 July.
Submit Your Tax Return
Before clicking submit, double-check:
- All figures are accurate
- Claimed expenses are legitimate
- Your personal details are correct
- You haven’t missed any income sources
After submission, HMRC provides:
- Submission confirmation on screen
- Reference number for your records
- Email confirmation (if you’ve enabled notifications)
How to Pay Your HMRC Tax Bill
Filing your return does NOT automatically pay your tax bill. Payment must be made separately before the 31 January deadline.
Fast and secure — use HMRC’s bank details
Pay directly through HMRC’s website
Set up automatic payments in advance
For large payments or same-day clearance
Official HMRC payment guide: Pay your Self Assessment tax bill on GOV.UK →
Common HMRC Tax Return Mistakes to Avoid
❌ Missing registration deadlines
Registering late can trigger penalties even before you file.
❌ Forgetting additional income sources
All income must be declared — HMRC shares data with banks and platforms.
❌ Claiming personal expenses
Only business expenses are allowable. Personal spending raises red flags.
❌ Entering incorrect turnover figures
Double-check your numbers — mistakes can trigger HMRC enquiries.
❌ Ignoring payments on account
These are mandatory if your bill exceeds £1,000. Budget for them.
❌ Not keeping proper records
HMRC can ask for evidence up to 5 years after filing.
Frequently Asked Questions
Can I submit my HMRC tax return myself?
Yes. Most people can file their Self Assessment tax return online themselves through the HMRC website. The system is designed to be user-friendly with clear instructions.
What happens if I miss the HMRC deadline?
HMRC issues an automatic £100 late filing penalty immediately after 31 January. After 3 months, daily penalties of £10 per day apply (up to £900). After 6 months, further penalties of £300 or 5% of tax due apply.
How long does it take to file a tax return online?
If your records are organised, most online tax returns take between 1–3 hours to complete. First-time filers may take longer as they familiarise themselves with the system.
Do I need an accountant?
Simple tax returns can often be filed independently. However, complex finances (multiple properties, foreign income, capital gains, trusts) usually benefit from professional tax advice.
What’s the difference between filing and paying?
Filing is submitting your tax return. Paying is sending the money you owe. You must do BOTH by 31 January. Filing alone does not pay your tax bill.
Making Tax Digital — What’s Changing?
HMRC is rolling out Making Tax Digital for Income Tax Self Assessment (MTD for ITSA) from April 2026. Instead of one annual return, you’ll submit quarterly updates via compatible software if your income exceeds £50,000 (£30,000 from April 2027).
This is a significant change. The best time to prepare is now — start using digital record-keeping software to build good habits before it becomes mandatory.
Final Thoughts
Submitting your HMRC tax return online may feel intimidating initially, but the process becomes straightforward once you understand the steps involved.
The biggest mistake most people make is delaying the process until the final days before the deadline. Staying organised throughout the year, keeping accurate records, and submitting early can save you significant stress, penalties, and financial surprises.
Whether you’re self-employed, a landlord, freelancer, or company director, filing correctly and on time helps you stay compliant with HMRC while claiming every legitimate tax relief available to you.
Don’t want to deal with HMRC’s online system yourself? Our ACCA-qualified accountants can file your Self Assessment tax return for you — accurately and on time.
How it works: Simply fill out our quick form with your income and expense information, make the advance payment (mandatory), and our team will prepare and submit your tax return to HMRC before the deadline.