A limited company is a separate legal person from you. That single idea explains almost everything in your first three months: the company needs its own bank account, its own tax registrations, its own records, and its own money kept apart from yours. Get those foundations right in the first 90 days and the rest of year one is routine. Get them wrong and you spend January untangling it. Here is the order to do things in.
Weeks 1 to 2: the foundations
Open a business bank account first. Before the first invoice, before the first purchase. Every pound that comes in or goes out should pass through an account in the company's name. Paying a company cost from your personal card is fixable; running the company from your personal account for two months is a mess. Digital banks open accounts in a day or two; high street banks take longer, so start now.
Watch the post. Within about three weeks of incorporation, HMRC writes to your registered office with the company's Unique Taxpayer Reference (UTR), a ten-digit number you will need for everything tax-related. It is not the same as your personal UTR. If it has not arrived after three weeks, request it on GOV.UK.
Set up your Government Gateway and business tax account. This is the online login for all the company's taxes. Create it now, add the Corporation Tax service when the UTR arrives, and add PAYE and VAT as you register for them.
Write down two dates. Your date of incorporation and your accounting reference date, which Companies House sets automatically as the last day of the month your company was formed in. Every deadline in this article hangs off those two dates.
Within 3 months of trading: register for Corporation Tax
This is the step people assume is automatic. Companies House tells HMRC your company exists, but you must still tell HMRC the company is active, within 3 months of starting to do business. "Doing business" is broader than making a sale. HMRC also counts advertising, renting premises, hiring someone or buying stock, so the clock usually starts before your first invoice. You register online using the company UTR and your Government Gateway login, giving your trading start date and accounting period. Register late and HMRC can charge a penalty. If the company is genuinely not doing anything yet, tell HMRC it is dormant instead.
One quirk that catches nearly every new company: Companies House sets your first accounts period to run from the day you incorporated to your accounting reference date, the last day of that month a year later. So it is almost always a little longer than 12 months. HMRC, however, will not accept a Corporation Tax accounting period longer than 12 months, so it splits that first period in two: one return for the first 12 months and a second for the few days or weeks left over. Two Company Tax Returns for one set of accounts, each with its own payment date. Your accountant will handle it, but it explains a letter that otherwise looks like a mistake.
Before your first payday: register for PAYE
If the company is going to pay you a salary, it is an employer, and it must run PAYE even with a single employee who is also the director. Registering has a window, and it is stricter than people expect. You can only register as an employer inside a window: no earlier than two months before your first payday, because HMRC will not accept it before then, and no later than about three weeks before, because HMRC takes up to 15 working days to send the employer PAYE reference you need to run the first payroll. Miss the window and you cannot pay yourself on the planned date. You will need the company's UTR, registered office, your details as director, the planned first payday and the number of employees. So decide your first payday early and count back. Once registered, every payday the company submits a Real Time Information report to HMRC on or before the day you are paid.
Why bother with a salary at all? Because for most single-director companies in 2026/27 the efficient structure is a salary of £12,570 a year, exactly your Personal Allowance, with the rest taken as dividends. The salary carries no Income Tax and no employee National Insurance, counts towards your State Pension, and reduces the company's Corporation Tax. The only cost is employer National Insurance of (£12,570 − £5,000) × 15% = £1,135.50, which the Corporation Tax relief comfortably outweighs. The full reasoning, with the situations where it changes, is in our director salary and dividends guide, and you can run your own numbers in the director take-home calculator.
Decide about VAT
You must register once taxable turnover passes £90,000 in any rolling 12 months, or if you expect to pass it in the next 30 days. Below that it is your choice. Registering voluntarily makes sense if your customers are mainly VAT-registered businesses (they reclaim what you charge, and you reclaim VAT on your costs) or if you have heavy start-up costs with VAT on them. It rarely makes sense if you sell to the public. Our VAT registration guide goes through the threshold in detail.
Day one: software and receipts
Choose cloud accounting software and connect it to the business bank account before the first transaction lands. We use Xero with clients, but the principle matters more than the brand: every transaction flows in automatically, you attach the receipt from your phone the same day, and your accountant sees the same live picture you do. Do not plan to "sort the receipts at year end". Nobody ever does, and the missing ones cost you tax relief.
Know your deadlines: they are fixed the day you incorporate
These dates now apply to you, and they apply even if the company never trades. Take a company incorporated on 15 September 2026: its accounting reference date is 30 September, so the first accounts run from 15 September 2026 to 30 September 2027, and HMRC splits that into two tax periods, 15 September 2026 to 14 September 2027 and 15 to 30 September 2027.
| Obligation | Rule | Example date |
|---|---|---|
| Confirmation statement | Within 14 days of the end of each 12-month review period (£50 online) | By 29 September 2027 |
| First annual accounts to Companies House | 21 months after incorporation (then 9 months after each year end) | By 15 June 2028 |
| Corporation Tax payment, first period | 9 months and 1 day after the tax period ends | By 15 June 2028 (period to 14 September 2027) |
| Corporation Tax payment, second period | 9 months and 1 day after the tax period ends | By 1 July 2028 (period to 30 September 2027) |
| Company Tax Returns (two CT600s) | 12 months after each tax period ends | By 14 September 2028 and 30 September 2028 |
Notice that the tax is paid before the return is filed, which surprises almost every new director. And the confirmation statement is due even when nothing has changed; it is Companies House checking your details are still right. Missing any of these triggers automatic penalties with no warning letter: late accounts start at £150 and rise to £1,500, and HMRC charges £200 the day after a late CT600. All the recurring dates are on our key dates page, and our first-year deadlines calculator works out your own dates from your incorporation date and sends them to your calendar.
Your own tax return. Plan to file a Self Assessment return every year as a director. Strictly, HMRC requires one if you have untaxed income (dividends above £500, benefits, other income) or if HMRC sends you a notice to file, which covers nearly every director who takes dividends, so most accountants register directors from day one. Register by 5 October after the end of the tax year, then file and pay by the following 31 January. Your dividend tax lands in that January bill, so keep a personal pot for it alongside the company's Corporation Tax savings.
You can change your year end. Many directors move the accounting reference date to 31 March so the company year lines up with the tax year, which makes dividend planning simpler and can tidy away the split first period. You tell Companies House online, and HMRC follows. You can shorten the period as often as you like, but you can only extend it once every five years, to a maximum of 18 months, and you cannot change it while accounts are overdue. Do it early, before the first year end, and it costs nothing.
Start saving for tax from the first invoice
The company's first Corporation Tax bill will not arrive for well over a year, which is exactly why it catches people. Move a percentage of every month's profit into a separate savings account as you go. At the 19% small profits rate, a company making £4,000 of profit a month should set aside £4,000 × 19% = £760 a month; by the time the bill arrives there is £9,120 waiting for it, plus interest. Your own dividend tax lands through Self Assessment the following January (see below), so a second, personal pot for that is wise.
The five mistakes new directors make in month one
- Paying personal costs from the company account. Every one becomes a loan from the company to you, and unpaid director's loans attract tax. Two pockets, from day one. Our expenses guide covers what the company can and cannot pay for.
- Drawing money without paperwork. A transfer to yourself is not a dividend until the decision is recorded in board minutes, a dividend voucher is issued and there is enough profit to cover it. Set up a monthly routine: salary through payroll, dividends declared properly.
- Assuming Corporation Tax registration happened automatically. It did not. Three months from your first business activity.
- Not saving for the tax. See above. The bill is real; it is just late.
- Forgetting the confirmation statement. It is small, cheap and easy to overlook a year after the excitement of forming the company. Diarise it now.
When to get an accountant involved
Honestly: before the first payroll run and the first dividend, not at year end. The expensive mistakes in a company's first year are structural, made in the first weeks, and cheap to prevent but slow to undo. A good accountant at day one sets up the payroll, the software, the dividend routine and the deadline calendar so that the rest of the year is genuinely boring, which is the goal.
That first-90-days setup is exactly what SJE Capital does for new companies: registrations, payroll, software, your pay structure and every filing from day one, for a fixed monthly fee.
Sources: GOV.UK guidance on registering for Corporation Tax, registering as an employer, filing annual accounts and confirmation statements. Correct for the 2026/27 tax year and reviewed September 2026. General guidance, not advice on your circumstances.
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