Self-assessment · N3
Self-Assessment Tax Return Accountant in Finchley
Filed accurately and early, not in the last week of January. We are based in Finchley and act for people across North London who have to file — and plenty who did not know they did.
The return itself is rarely the difficult part. What costs people money is finding out late that they were required to file, missing a relief they were entitled to, or discovering in January that the bill includes half of next year's tax as well. All three are avoidable with a few weeks' notice.
Our office is in Finchley (N3) and we prepare returns for employees, directors, sole traders, landlords and partners across North London.
Filed early, not in January
You know the figure months before you have to pay it.
Every relief checked
Pension, Gift Aid, professional subscriptions, working from home.
Payments on account explained
And reduced where your income has genuinely fallen.
Late or missing returns
Catch-up filings and dealing with HMRC where penalties have built up.
Self-assessment across North London
We prepare self-assessment returns for people all over North London, from Finchley and Barnet to Hendon, Muswell Hill and Enfield. The list of who has to file is further down this page. Below are the situations that most often bring someone to a return for the first time, and the dates that go with it.
The self-assessment calendar
- 5 October after the tax year ends: register, if you have not filed before and now need to
- 31 October: paper return deadline
- 31 January: online return deadline, balancing payment and first payment on account for the new year
- 31 July: second payment on account
Missing 5 October is easy to do, because nothing reminds you. If you register late and tax ends up paid late as a result, interest runs from the normal due date and a penalty for failing to notify can apply on top.
Selling online
Since 1 January 2024, eBay, Amazon, Etsy, Vinted, Airbnb and similar platforms have reported seller income to HMRC. Someone selling goods is left out only if they make fewer than 30 sales and receive less than €2,000 (about £1,700) in the year; there is no such exception for letting out property. Being reported does not mean you owe tax. Clearing out your own belongings is not trading, and the £1,000 trading allowance covers small side income. But if you are buying to resell, or renting out a room or flat, a return may well be due, and HMRC can now see the figures before you file.
Selling a property that is not your home
Gains on residential property are taxed at 18% or 24%. UK residents have to report the sale and pay any tax due within 60 days of completion, through a separate property return. Your usual self-assessment return does not replace that deadline. The gain is included on the annual return as well, and the payment already made is credited against it.
Making Tax Digital from April 2026
Since 6 April 2026, sole traders and landlords with qualifying income over £50,000 have had to keep digital records and send quarterly updates. The threshold falls to £30,000 from April 2027 and £20,000 from April 2028. If you expect to cross one of those lines, the time to set up the software is the year before.
Who has to file
Being on PAYE does not exempt you. HMRC does not always write to tell you either, and "I did not know" is not a reasonable excuse once a penalty has been issued.
- Self-employment or a share of a partnership
- Income over £100,000 not fully taxed through PAYE, where the personal allowance tapers away
- The High Income Child Benefit Charge, where a household earner crosses the threshold
- Rental income above the property allowance
- Dividends or savings interest above the allowances
- Capital gains, including a second property or a share disposal
- Untaxed foreign income, or a claim under the foreign income and gains regime that replaced non-domiciled status in April 2025
The deadlines and what missing them costs
The online filing deadline is 31 January following the end of the tax year, and the tax is due the same day. Miss the filing date and there is an immediate £100 penalty even if no tax is owed. After three months daily penalties start accruing, and further charges follow at six and twelve months. Late payment carries separate penalties and interest on top.
If you have already fallen behind, the position is usually recoverable. We file the outstanding returns, work out what is genuinely due, and where there is a reasonable excuse we make that case to HMRC rather than assuming the penalties are fixed.
Payments on account
Once your bill passes a modest threshold, HMRC asks for the tax on 31 January and half of next year's estimate on the same day, with the other half in July. In a first profitable year that turns one expected payment into one and a half at the worst moment. It is not a penalty, but it needs planning for — and if your income has genuinely dropped, the payments can be reduced rather than paid and reclaimed.
Making Tax Digital for income tax
Self-assessment is being replaced for the self-employed and for landlords above an income threshold. Instead of one return a year there will be quarterly updates from software, and a final declaration after the year end.
It is being introduced in stages by income level, so the date it starts affecting you depends on your turnover from self-employment and property combined — not on profit, and not on each source separately, which is the detail most people get wrong when working out whether it applies to them yet.
The practical consequence is that paper records and a shoebox in January stop being an option. Anyone in scope needs bookkeeping that runs during the year. That is worth setting up calmly in advance rather than in the quarter it becomes compulsory.
What to send us, and when
The return is quick when the information arrives together and slow when it comes in pieces. What is usually needed: P60 and P45s, P11D if you have benefits, bank interest, dividend vouchers or a statement, rental income and expenses, self-employment records, pension contributions, gift aid donations, and details of anything sold at a gain.
The two most commonly forgotten are pension contributions made personally — which higher-rate taxpayers have to claim through the return to get the rest of the relief — and gift aid, for the same reason.
Sending it in September rather than January is not about our convenience. Filing early tells you the bill months before it has to be paid, and it is the only way to reduce a payment on account before it is taken.
If you have missed a return, or several
This is more common than people think and it is almost always more fixable than they fear. The thing worth knowing before anything else is that the outcome depends heavily on how HMRC finds out.
Penalties are based on behaviour
The size of a penalty is not fixed by the amount of tax. It is set by the reason for the error — a genuine mistake despite reasonable care, carelessness, or a deliberate act — and then adjusted by how much you help put it right. Telling HMRC before they ask, explaining fully and giving them access to the records can reduce a penalty very substantially, in some cases to nothing.
Coming forward is cheaper than being found
An unprompted disclosure attracts a lower penalty range than one made after HMRC has opened an enquiry. That gap is the whole reason to act now rather than wait: the same facts, disclosed in a different order, produce a materially different bill. There are formal disclosure routes for exactly this situation.
How far back it goes depends on why
The number of years HMRC can assess is longer where the failure was careless, and longer again where it was deliberate. That is another reason the characterisation matters as much as the arithmetic, and why it is worth having the conversation before writing anything down.
Bring what you have, not what you wish you had
Nobody expects complete records for a year you did not know you had to declare. Bank statements are usually enough to reconstruct a workable picture, and where a figure genuinely cannot be established there is a proper way to estimate and disclose that it is an estimate. What does not work is a silence that continues.
More than a tax return
This page is about personal tax returns. If you also need accounts for a company, bookkeeping, VAT or payroll, or an accountant close to N3 for your business as a whole, our page on accountants in Finchley covers the full practice. The returns themselves are prepared by the same team either way.
Our services in Finchley
The services we provide in Finchley include property tax and bookkeeping. Each has its own page with what is included and how we work.
Frequently asked
When should I send you my paperwork?
As soon after 6 April as you can. Filing early does not mean paying early — the payment date is still 31 January — but it means you know the figure with months to plan for it, and any refund arrives sooner.
I have not filed for a few years. What happens?
We file the outstanding years, establish what is actually due, and deal with HMRC on the penalties. Coming forward voluntarily is treated considerably better than being found, so the sooner it starts the better the outcome.
What records do you need?
P60 or P45, P11D if you had benefits, details of any self-employment income and expenses, rental statements, dividend vouchers, pension contributions and Gift Aid donations. If you are not sure whether something counts, send it — sorting it is quicker than guessing.
Can you deal with HMRC for me?
Yes. Once you authorise us as your agent we can speak to HMRC on your behalf, which saves you the hold time and means the conversation is had by someone who knows what they are being asked.
Will I have to file quarterly?
Eventually, if you are self-employed or a landlord above the income threshold. Making Tax Digital replaces the annual return with quarterly updates from software and a final declaration. It is phased in by income level, and the test is combined self-employment and property turnover rather than profit — which is what most people get wrong when checking whether it applies to them yet.
Why file early if the deadline is January?
Because knowing the bill in September and paying it in January is a better position than finding out in January. Filing early also gives you the chance to reduce a payment on account before it is taken, which cannot be done retrospectively.
I have not filed for three years. What happens now?
Less than you are probably imagining, provided you go first. Penalties are set by behaviour and reduced by disclosure, and an unprompted disclosure sits in a much lower range than one that follows an HMRC enquiry. The usual route is to establish the years involved, reconstruct the income from bank records, and disclose the lot together with a proposal for paying. People routinely come in expecting the worst and leave with a payment plan.
Will I go to prison?
For an unfiled return where you come forward and cooperate, effectively no — this is dealt with through penalties and interest. Criminal prosecution is reserved for deliberate, sustained fraud, and even then is rare relative to the number of cases settled civilly. The behaviour that changes the picture is concealment after being asked, which is an argument for disclosing now rather than a reason to delay.
I do not have receipts for those years. Can anything be done?
Yes. Bank and card statements will usually carry enough to reconstruct income and most expenditure, and where a figure cannot be established there is an accepted way to estimate it and say plainly that it is an estimate. HMRC deals with reconstructed figures routinely. An honest reconstruction is fine; a confident number you cannot support is not.
I became self-employed this year. When do I have to register?
By 5 October after the end of the tax year in which you started. So if you started trading between 6 April 2026 and 5 April 2027, you must register by 5 October 2027. Your first return and payment are then due by 31 January 2028. Register as soon as you start, though, because you need your reference number before you can file, and it can take some time to arrive.
I sell things on Vinted and eBay. Do I need to file a return?
Not just because the platform has reported you. Platforms report sellers of goods who make 30 or more sales, or receive €2,000 (about £1,700) or more, in a year, but selling your own used belongings is not trading. The £1,000 trading allowance also covers small genuine side income. If you buy things to resell, or regularly make items to sell, you are probably trading. Once your income goes over the allowance, a return is needed.
I sold a buy-to-let flat. Is my normal tax return enough?
No. As a UK resident you must report the sale and pay any capital gains tax within 60 days of completion, through a separate HMRC property return. The gain, taxed at 18% or 24%, also goes on your annual self-assessment return, and the payment already made is credited against it. Missing the 60-day deadline brings penalties even if the annual return is filed on time.
Get your return out of the way
Send us what you have and we will tell you what is missing, what it will cost, and what the bill is likely to be.
Get in touchWe respond within one working day.
Local to you
Chartered accountants, just up the road.
We are based in Finchley and work across North London. Come in, call, or do the whole thing by email — whichever suits you.
Or call 07480 281548