Dormant company rules, telling HMRC within 3 months, pre-trading expenses you can claim, and the checklist to complete before your first sale.
Zazentax Startup Series, Part 3 of 3 · Updated July 2026 · Reading time: about 8 minutes
There is a distinctive moment in every new business. The registration is done, the congratulations have been received, and yet nothing has been sold. On the United Kingdom’s business forums this moment produces a recognisable cluster of questions. Do I need to tell anyone I have not started yet? Can I claim the things I am buying now? Is there anything I must file even though there is no income? The questions are good ones, because this quiet window carries real obligations and, used well, real advantages.
This article assumes the registration step is behind you, whether as a limited company or as a sole trader, and deals with what comes next. Before proceeding, one definition is essential, because almost everything below hangs on it.
What “Trading” Means, Because the Clock Starts There
HMRC (His Majesty’s Revenue and Customs, the United Kingdom tax authority) does not define trading as your grand opening. A business is generally trading, or “active”, once it is carrying on business activity: selling goods or services, but also buying stock in order to sell it, advertising for customers, or earning any business income, including interest. Consequently, you can be trading in HMRC’s eyes weeks before your first invoice, and preparatory steps such as ordering inventory can be the trigger.
Genuinely preparatory activity, such as writing a business plan, researching suppliers or building a website you have not launched, does not normally count. The boundary matters because two different sets of duties apply on either side of it.
If You Formed a Limited Company: Two Parallel Authorities
A new company deals with two separate bodies, and forum threads show how often they are conflated. Companies House is the registrar: it records your company’s existence, directors and filings. HMRC is the tax authority: it collects the company’s taxes. Registering with one does not complete your duties to the other.
While the company is not yet active, it is “dormant” for corporation tax purposes, and HMRC can be told so. However, dormancy removes no Companies House duties: the company must still file an annual confirmation statement (a filing confirming that the registered details are correct) and annual accounts, which for a company that has never traded are simplified dormant accounts. A registered company with no sales still has filing deadlines, and missing them incurs automatic penalties.
Once the company becomes active, you must tell HMRC within three months of the start of business activity and register the company for corporation tax. This is done online using the company’s Government Gateway account and its Unique Taxpayer Reference, usually shortened to UTR, the ten-digit number HMRC posts to the registered office shortly after incorporation. Keep that letter; a striking share of forum distress traces back to a discarded UTR.
Action required: Mark the three-month rule now. The deadline runs from when the company starts any business activity, not from when you feel launched. Late notification can lead to penalties, and the definition of activity is wider than most new directors expect.
In addition, note a duty introduced recently: directors and people with significant control must verify their identity with Companies House. Identity verification became mandatory for new appointments from 18 November 2025, and existing directors must be verified by 18 November 2026 at the latest, or before the company’s next confirmation statement if that is earlier. Verification is free through GOV.UK One Login, the government’s identity service, and produces a personal code you will need for future filings.
If You Registered as a Sole Trader: One Authority, One Deadline
The sole trader position is simpler but still misunderstood. You must be registered for Self Assessment, the system through which individuals report untaxed income, by 5 October following the end of the tax year in which you started trading. Tax years run from 6 April to 5 April; therefore, if your first sale happens in August 2026, that falls in the 2026/27 tax year and the registration deadline is 5 October 2027. Registering early costs nothing and removes the risk of forgetting.
One threshold is worth knowing before your first sale. If your total gross trading income in a tax year is £1,000 or less, the trading allowance can exempt it entirely, and registration may not be required at all. The allowance suits genuine small-scale selling; however, once income passes £1,000, or you want to claim actual expenses instead of the flat allowance, normal registration and record keeping apply. You cannot claim both the £1,000 allowance and your real expenses, so businesses with meaningful costs almost always do better claiming expenses.
The Pre-Trading Advantage Most New Owners Miss
Money spent before trading begins is not lost for tax purposes. Expenditure incurred up to seven years before your first day of trading can generally be claimed as if it were spent on that first day, provided two conditions hold: it was incurred wholly and exclusively for the business, and it would have been an allowable expense had you already been trading. Stock, equipment, insurance, website costs, domain names, professional fees and pre-launch advertising commonly qualify. Certain items do not, notably company formation costs and most training that gives you brand new skills rather than updating existing ones.
The rule has one demanding implication: evidence. A receipt from the quiet window may not be needed until your first tax return, many months later, and must then survive the full retention period beyond that. Accordingly, your record keeping system should exist before your business does. Part 1 of this series sets out a twenty-minute weekly system that satisfies HMRC’s requirements from day one.
Key point: Keep every receipt from the pre-trading period, however small. This spending is claimable on your first return, and unclaimed pre-trading costs are a permanent overpayment of tax, not a rounding error.
A Checklist for the Quiet Window
The following sequence covers what experienced owners, with hindsight, say they wish they had done before their first sale.
- Open the bank account. A limited company needs its own account because the company’s money is legally separate from yours. A sole trader is not obliged to have one, but separation makes every later step easier.
- Set up the record system. Choose software or a disciplined folder structure, and start photographing receipts immediately, including pre-trading purchases.
- File the government letters. Keep the company UTR letter, Government Gateway credentials and Companies House authentication code together and accessible.
- Complete identity verification if you are a company director, and diarise the confirmation statement and accounts deadlines shown on the Companies House register.
- Plan the VAT watch. Registration for VAT (Value Added Tax) becomes compulsory once taxable turnover in any rolling twelve-month period exceeds £90,000, and the check is monthly, not annual. Decide now where you will track the rolling total; some businesses also register voluntarily below the threshold to reclaim VAT on costs.
- Register as an employer only when needed. PAYE (Pay As You Earn, the system for deducting tax from wages) registration is required before the first payday if you will employ anyone, including paying yourself a salary as a director.
- Diarise the three-month rule so that the day you start selling, buying stock or advertising, telling HMRC is already on the list.
The Mistakes This Window Is Designed to Prevent
Reading several hundred forum threads from new owners reveals the same failures on repeat: business and personal money mixed in one account for a year; the UTR letter lost and the corporation tax registration stalled; dormant companies fined for confirmation statements nobody knew were due; pre-trading receipts discarded and their tax value with them; and the VAT threshold crossed unnoticed because turnover was only checked at year end. None of these requires expertise to avoid. Each requires only that the quiet window is used as a setup period rather than a waiting room.
Key Takeaways
- Trading starts, in HMRC’s eyes, with business activity such as buying stock or advertising, not with your launch day.
- A company must tell HMRC within three months of becoming active; a dormant company still owes Companies House its annual filings.
- Sole traders must be registered for Self Assessment by 5 October after the end of their first trading tax year.
- Costs incurred up to seven years before trading can usually be claimed on the first return, but only if the evidence was kept.
- Bank account, record system, identity verification and a VAT watch belong in place before the first sale, not after it.
About to Make Your First Sale?
Get your pre-trading checklist reviewed by Zazentax, so you enter your first trading year with every obligation covered and every claimable cost captured.
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Hey, I am Andrei Spătaru. I am determined to make a business grow. My only question is, will it be yours?
