I missed the 5 October 2026 registration deadline. What now?

Register now. GOV.UK says telling HMRC after 5 October 2026 could lead to a penalty. A failure to notify penalty may arise if you register after 5 October and do not pay all of your tax bill by 31 January, and it is based on the amount still left to pay. HMRC's factsheet CC/FS11 says no failure to notify penalty is charged where you had a reasonable excuse, the failure was not deliberate, and you told HMRC without unreasonable delay once the excuse ended. Either way, the 2025/26 tax is due by 11:59pm on 31 January 2027.

How long will my UTR take to arrive?

Allow weeks if you register by post. Online registration puts your UTR in your personal tax account within 72 hours. By post it usually arrives in 15 working days, or 21 days if you are abroad, and can take longer in busy periods. If you do not live in the UK and are not self-employed, you cannot register online: the route is form SA1 by post. The UTR is a 10-digit number, and you must be registered before an agent can be authorised to act for you.

What happens if my 2025/26 return is filed late?

Penalties start at once and build. A late return gets an initial £100 penalty. After 3 months, daily penalties of £10 a day apply, up to £900. After 6 months there is a further 5% of the tax due or £300, whichever is greater, and the same again after 12 months. Late payment brings penalties of 5% of the unpaid tax at 30 days, 6 months and 12 months, plus interest at Bank of England base rate plus 4%. You can appeal with a reasonable excuse, usually within 30 days of the penalty being issued.

I have earlier years I never filed. Do I just file them all now?

Not always. The route depends on what was missed. Work out first whether tax is actually due. Where UK tax is due on offshore income, the route is the Worldwide Disclosure Facility: you notify HMRC through the Digital Disclosure Service, then have 90 days to submit the disclosure and pay. Undeclared UK residential rent usually fits the Let Property Campaign. How far back you go depends on behaviour: broadly 4 years with reasonable care, 6 if careless, up to 12 for offshore matters and up to 20 where deliberate or where you failed to notify. Where a return was filed but is wrong, a 2024/25 return can usually be changed until 31 January 2027.

Can I file my first return through HMRC's free online service?

Not if you need the SA109. Non-residents cannot use HMRC's online services to report their income. The SA109 pages, which carry non-residence, split year and any FIG claim, can only be filed online through commercial software or a professional agent. A paper return must reach HMRC by 11:59pm on 31 October 2026 or a late filing penalty applies, so for most people filing now an online return through commercial software or an agent is the practical option. Horizon files the SA109 as your authorised agent, online, so the online deadline applies: 11:59pm on 31 January 2027. If you register late, HMRC's letter gives you a filing deadline of 3 months from its date; the tax is still due by 31 January 2027.

Do I need to be registered before I instruct an adviser?

To authorise an agent, yes. GOV.UK says you must register for Self Assessment before you authorise an agent, which is done through Online Agent Authorisation or the 64-8 paper form. An agent registering a client who is not self-employed or a director uses form SA1, and the client's postal address can be outside the UK. You can still book the clarity call and gather papers while you wait. You remain legally responsible for your own tax and check the return before it is submitted.

First or late return for 31 January 2027

Your first UK tax return, filed properly before 31 January 2027.

Never filed, missed the 5 October registration date, or carrying earlier years? Register now, file 2025/26 by 31 January 2027, and put the past right before HMRC asks.

Online filing deadline: 31 January 2027

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The Short Answer

It is not too late. The 5 October 2026 registration date for 2025/26 has passed, but the standard online deadline is 11:59pm on 31 January 2027, and the tax is due by then whatever date HMRC gives you for the return. Register now. Registering late risks a penalty, but paying the 2025/26 tax in full by 31 January 2027 keeps that risk low. Register, file and pay the 2025/26 tax in full by 31 January 2027.

Registration takes longer than people expect, and longer still from abroad, where anyone who is not self-employed must use a paper form. You must be registered before we can act for you as your agent. Start now: book the clarity call and gather your papers while HMRC issues your UTR. HMRC then sends a letter or email with your filing date. Whatever date it gives, the tax is still due by 31 January 2027.

Earlier years need a different route, and timing drives the penalty: an unprompted disclosure usually costs far less than one HMRC prompts. Horizon UK Tax Solutions is a founder-led Chartered Tax Adviser practice. We prepare and file first returns, late returns and the SA109 pages that HMRC's free online service cannot file, on published fixed fees. We are rated 5.0 on Google from 19 reviews, with seven years at a Big Four firm behind the advice. Start with a free 30-minute clarity call.

Is This You?

Who this return is for

You arrived in the UK during 2025/26, have foreign income or gains, and have never filed a UK return.
You missed the 5 October 2026 registration date and still need your 2025/26 return filed by 31 January 2027.
You had untaxed income in 2025/26, such as rent, savings interest, dividends or foreign income, for the first time.
You live abroad with UK income, such as rent from a UK property, and cannot file through HMRC online.
You have earlier tax years outstanding and want to come forward before HMRC writes to you first.

What Goes on Your Return

Pages	What they cover
SA100	The main return. If your only foreign income was untaxed interest of up to £2,000, it can go in box 3 here, unless you claim FIG relief on foreign income (SA109 box 28).
SA109	Residence and FIG regime pages: non-residence, split year and FIG claims for income and gains. HMRC's free online service cannot file it.
SA106	Foreign pages for UK residents: overseas interest over £2,000 and foreign dividends over £500, or all untaxed foreign interest and foreign dividends, whatever the amount, if you claim FIG relief on foreign income (SA109 box 28), converted to sterling at the rate when the income arose. Not used by a non-resident completing the SA109.
SA105	UK property pages, including a non-resident landlord's rent and any tax already deducted under the scheme.

What We Do

Handled for you, end to end

A free 30-minute clarity call to establish which years are due, which pages you need, and what to fix first.
A fixed fee confirmed before any work starts, using our published return fees, with any advisory work quoted in writing. Never hourly.
Identity and address checks first, as anti-money-laundering rules require, then your documents uploaded to our secure client portal.
We prepare your 2025/26 return, including SA109, SA106 and SA105 pages, FIG and split-year claims, and foreign tax credit relief.
You review and approve the return. We file it as your authorised agent and confirm exactly what to pay and when.
Where filing is needed in another country, we lead on the UK position and coordinate vetted specialists there.

Start Now

What to gather

Records take longer to collect than the return takes to prepare. Start with this list, then upload what you have to your secure client portal.

1Your UTR, or the date and method you used to register for Self Assessment
2Your UK National Insurance number, if you have one
3Your UK arrival or departure dates and a day count for 2025/26
4UK employment pay and tax figures for 2025/26 from your employer's year-end paperwork
5Overseas bank and broker statements showing interest, dividends and any disposals
6Rental income and expenses for each property, plus any NRL6 certificate of tax deducted
7Foreign tax paid on each source, and the date each amount of income arose
8A list of earlier years with income HMRC has not been told about
9Every HMRC letter received, including notices to file, penalties or letters about overseas income

Key Dates for 2025/26

5 October 2026
Last day to register for Self Assessment for 2025/26 if you have never filed before or did not file for 2024/25
31 October 2026
Paper 2025/26 return must reach HMRC by 11:59pm
30 December 2026
Online 2025/26 return deadline (11:59pm) to have a bill under £3,000 collected through your PAYE tax code
31 January 2027
Online 2025/26 return deadline, 11:59pm
31 January 2027
Pay the 2025/26 balancing payment and the first payment on account
31 January 2027
Usual last day to amend a 2024/25 return
1 February 2027
Return now late: initial £100 late filing penalty applies (derived: day after 31 January deadline)
2 March 2027
30 days after 31 January: 5% late payment penalty on 2025/26 tax still unpaid at this point (derived)
6 April 2027
Making Tax Digital for Income Tax starts for anyone with qualifying income over £30,000 in 2025/26
1 May 2027
Return 3 months late: £10 daily penalties start, up to £900 (derived)
5 July 2027
Letting agents and tenants must give non-resident landlords their NRL6 certificate for 2026/27
31 July 2027
Second payment on account due
31 July 2027
6 months after 31 January: a further 5% late payment penalty on 2025/26 tax still unpaid (derived). The 6-month late filing penalty follows from 1 August 2027.

How It Works

From first call to filed

1
Free clarity call
A free 30-minute call directly with the adviser. We work out which pages your return needs, whether a FIG or split-year claim is in play, and what you will need to gather.
2
Fixed quote and ID checks
You get a fixed fee, agreed in writing before anything starts. Anti-money-laundering rules require identity and address checks first, so we complete those before any work on your return begins.
3
Documents to the portal
You upload statements, certificates and records to a secure client portal. Everything is handled remotely, for clients across six continents.
4
Prepare, approve, file
We prepare the return. You review it and approve it. We file it with HMRC as your authorised agent and confirm exactly what to pay and when.

Fixed Fees

The fee is agreed before we start

First-time filers are priced on our published return fees. The Standard Personal Tax Return is £350. The Non-Resident and Expat Tax Return is £550. The Complex Personal Tax Return, for multiple income streams, investments, trusts or complex structures, is from £750. Earlier years and any disclosure are quoted as a fixed fee agreed in writing before work starts. Book a free clarity call and we will confirm which published fee applies.

Standard Personal Tax Return

£350

For individuals with straightforward tax affairs: accurate preparation and submission of your UK Self Assessment, whether you're employed, self-employed, or earning rental income, with all allowable expenses claimed.

Non-Resident & Expat Tax Return

£550

For internationally mobile individuals: handling cross-border taxation, multi-country income, and UK residency under the Statutory Residence Test, with correct reporting of overseas income.

Complex Personal Tax Return

£750+

For more sophisticated arrangements: multiple income streams, investments, trusts, and complex structures, with a detailed, tailored approach and proactive tax planning.

Fixed and agreed in writing before any work starts. No hourly billing. Full pricing

Common Questions

Honest answers, before you book

Read the guides first, if you like

Browse all guides

Non-Doms & Inbound

The First FIG Filing Season: 2025/26 Returns Due 31 January 2027

Nobody has ever filed a FIG claim before this filing season: 2025/26 was the regime's first year, and the returns that carry the first claims are due 31 January 2027. New boxes, a strict quantification rule, a 5 October registration deadline for new arrivers, and a first-year tax bill that can hit 150% of the year's liability. The timeline from August 2026 to January, month by month.

10 min read · Reviewed August 2026

Non-Doms & Inbound

FIG Tax Return: SA109 Boxes 28 and 29, HS266 Walkthrough

FIG tax return walkthrough built on HMRC helpsheet HS266: SA109 boxes 28 and 29 for 2025/26, the allowances a claim costs you, disclosure and records.

9 min read · Reviewed September 2026

Self Assessment

Expat Self Assessment: UK Tax Returns from Abroad

Living abroad does not switch off your UK tax return. This guide explains who still files, which pages non-residents need and the deadlines that apply from overseas.

13 min read · Reviewed July 2026

Non-Resident Landlords

NRL1 Form, NRL2 and Non-Resident Landlord Tax on UK Rent

UK rental income stays taxable in the UK however far away you live. What changes when you move abroad is how the tax is collected: the Non-Resident Landlord Scheme, form NRL1, your allowances and your filing route.

16 min read · Reviewed September 2026

Foreign Income

HMRC Worldwide Disclosure Facility & Nudge Letters Explained

The HMRC Worldwide Disclosure Facility explained: how a WDF disclosure works, what a nudge letter and Certificate of Tax Position mean, and what it costs.

9 min read · Reviewed July 2026

Self Assessment

Let Property Campaign: Disclosing Undeclared Rental Income

If you have UK rental income you never told HMRC about, the Let Property Campaign lets you come forward on the best terms available: penalties as low as 0% to 10% instead of up to 100%, on a settlement you calculate and offer yourself. Who qualifies, how far back the years go, and how the 90-day process actually runs.

11 min read · Reviewed August 2026

Quick answers

Free Tax Tools

Run your own numbers, before we speak

See all free tools

Accounting Fee Estimator

See an indicative fee for working with Horizon UK Tax Solutions. Answer a couple of questions about your situation for a starting figure. Every fee is fixed and agreed upfront, with no surprise bills.

Try it free

FIG Regime Eligibility Checker (4-Year Foreign Income & Gains)

Free tool: check whether you qualify for the UK 4-year FIG (Foreign Income and Gains) regime that replaced the non-dom rules, and how many of your four relief years remain. 2026/27.

Try it free

UK Statutory Residence Test Calculator

Free UK Statutory Residence Test calculator. Enter your UK days, work pattern and ties for an instant indication of whether you are UK resident, with the deciding test and full reasoning.

Try it free

Split-Year Treatment Case Finder & 5-Year Trap Checker

Free tool: find which of HMRC’s eight split-year cases applies when you move to or from the UK, and check whether the 5-year temporary non-residence trap could tax your gains on return. 2026/27.

Try it free

UK Income Tax & Take-Home Calculator

Work out your UK income tax, National Insurance and take-home pay, with a Scottish-taxpayer option for Scotland's separate income-tax bands. Indicative, instant, free.

Try it free

Other Returns We File

2025/26 returns, by situation

Ready When You Are

Start with a free clarity call

Book a free clarity call and we will talk through your situation and confirm a fixed price in writing: no obligation, no pressure, and no surprises.

Chat on WhatsApp

Prefer email? Reach us at jordanonraet-wells@horizonukts.com

Your first UK tax return, filed properly before 31 January 2027.

Who this return is for

Handled for you, end to end

From first call to filed

Free clarity call

Fixed quote and ID checks

Documents to the portal

Prepare, approve, file

The fee is agreed before we start

I missed the 5 October 2026 registration deadline. What now?

How long will my UTR take to arrive?

What happens if my 2025/26 return is filed late?

I have earlier years I never filed. Do I just file them all now?

Can I file my first return through HMRC's free online service?

Do I need to be registered before I instruct an adviser?

Read the guides first, if you like

The First FIG Filing Season: 2025/26 Returns Due 31 January 2027

FIG Tax Return: SA109 Boxes 28 and 29, HS266 Walkthrough

Expat Self Assessment: UK Tax Returns from Abroad

NRL1 Form, NRL2 and Non-Resident Landlord Tax on UK Rent

HMRC Worldwide Disclosure Facility & Nudge Letters Explained

Let Property Campaign: Disclosing Undeclared Rental Income

Run your own numbers, before we speak

Accounting Fee Estimator

FIG Regime Eligibility Checker (4-Year Foreign Income & Gains)

UK Statutory Residence Test Calculator

Split-Year Treatment Case Finder & 5-Year Trap Checker

UK Income Tax & Take-Home Calculator

2025/26 returns, by situation

Start with a free clarity call