Every limited company deadline in one sheet: accounts, Corporation Tax and confirmation statement

Who it’s for

Consultants, contractors and solo founders who run their own UK private limited company, whether they file everything themselves or have an accountant who does it

Time to set up

About 40 minutes once, then 5 minutes a quarter

Difficulty

Beginner

Monthly cost

£0

You help the director of a small UK private limited company keep track of its filing dates. I will paste text copied from the company's page on the Companies House register and, if I have them, from the company's HMRC business tax account or HMRC letters. Use ONLY what is written in the text: never guess a date, and do not work out or add any date that is not printed. PART 1, TABLE: one row per date printed in the text, with columns Company, What it is (for example Next accounts made up to, Accounts due by, Next statement date, Confirmation statement due by, Corporation Tax accounting period end, Corporation Tax payment due, Company Tax Return due), Date, and Source (Companies House or HMRC). Write dates as DD/MM/YYYY so I can paste the rows into Google Sheets. PART 2, GAPS: one line for anything missing or unclear, such as no HMRC dates in the text, a filing marked overdue, or two dates for the same thing that don't match. If nothing is missing, say so. PART 3, CALENDAR: for each due date in Part 1, one line I can use as a calendar event title, in the form Company: what is due, date (source). RULES: British English, plain and direct. Do not give tax or legal advice and do not mention penalties. If the text is cut off or doesn't say something you need, add a short note in brackets saying in plain words what to check, for example (check this date on the Companies House register). Text: [paste]

Your company’s year ended on 31 March. That one date sets four statutory deadlines, and none of them falls on 31 March. The accounts are due at Companies House on 31 December, and a day late costs a private company £150 (GOV.UK). The Corporation Tax is due on 1 January, which is a bank holiday, so the money needs to reach HMRC on 31 December (GOV.UK). The Company Tax Return is due the following 31 March, and a day late costs £200 (GOV.UK). Then there’s the confirmation statement, which runs on its own clock from the day you incorporated.

Two bodies, four clocks, and two of the deadlines in the same week as Christmas. If you run your consultancy through a limited company, it’s easy to know roughly when things are due and still get a date wrong, especially in the first two years, when the rules bend.

This year has added two more reasons to write it all down. HMRC’s free online service for filing accounts and the Company Tax Return closed on 31 March 2026 (GOV.UK), so anyone who used it needs a new way to file this year. And Companies House won’t accept a confirmation statement “until all directors have verified their identity” (GOV.UK).

This guide gets you a free Google Sheet that works out every date from two inputs, checks each one against the register, and turns red before you’re late.

What does this automation do?

1. You copy your company’s dates from its Companies House register page and your HMRC business tax account.
2. A short AI prompt turns that text into a table of dates to check, a list of anything missing, and calendar entries.
3. Google Sheets formulas work out each deadline from your year end and confirmation date: accounts, Corporation Tax payment, the last safe day to pay, the tax return and the confirmation statement.
4. A Check column compares each date with the one on the register, so a typo shows up straight away.
5. A Due soon tab and red and amber cells show what’s coming in the next 90 days.

What do you need before you start?

• A free Google account, for Sheets and Calendar.
• Your company number, so you can find it on the Companies House register, and access to your HMRC business tax account (or the last letter HMRC sent about Corporation Tax).
• A free ChatGPT, Claude or Gemini account, if you want the prompt to do the copying.
• About 40 minutes.

You don’t need an accountant to use it, and it doesn’t replace one. If you have one, it tells you when to send them the year’s paperwork and when to ask if it’s been filed.

How do I set it up?

Step 1: Copy your dates from the register and from HMRC

Search for your company on the Companies House register and open its overview page. It shows when the next accounts are made up to and when they’re due, and the next confirmation statement date and when it’s due. Copy the whole page.

Then sign in to your HMRC business tax account and find your Corporation Tax accounting period. HMRC sends a letter with the dates of your first accounting period after you add Corporation Tax to your business tax account (GOV.UK). Copy the period and any payment or return dates you can see.

Paste both into the prompt below. It gives you back every printed date in a table, with its source, and a list of anything missing. Check every row against the page it came from before you rely on it.

Why bother with the AI at all? The register page mixes dates you need with dates you don’t, and in a busy month it’s easy to copy the “made up to” date into the “due by” box. The prompt is told only to copy what’s printed, and not to work anything out. The working-out is the sheet’s job, because spreadsheets are good at date arithmetic and AI tools aren’t reliable at it.

Step 2: Build the Deadlines tab

Create a Google Sheet called “Company deadlines”. In File › Settings, set the locale to United Kingdom, so 01/04/2027 means 1 April and not 4 January. Name the first tab “Deadlines” and add these headings in row 1:

Use Data › Data validation on column D to make it a drop-down of the three row types. One row per year is enough for most companies. Add next year’s row when this year’s is done.

Add a second tab called “Holidays”. Put the heading “Date” in A1 and, from A2 down, the bank holidays for your part of the UK from GOV.UK’s list (GOV.UK). England and Wales, Scotland and Northern Ireland have different lists. Add the next two years’ worth.

Step 3: Add the accounts and Corporation Tax formulas

Put these in row 2 and fill them down.

E, Accounts due:

=IF(OR(C2="",D2="Short first tax period"),"",IF(AND(D2="First accounts",EDATE(B2,12)<=C2),MAX(IF(EDATE(B2,12)=EOMONTH(B2,12),EOMONTH(B2,21),EDATE(B2,21)),IF(C2=EOMONTH(C2,0),EOMONTH(C2,3),EDATE(C2,3))),IF(C2=EOMONTH(C2,0),EOMONTH(C2,9),EDATE(C2,9))))

F, Corporation Tax due:

=IF(C2="","",IF(C2=EOMONTH(C2,0),EOMONTH(C2,9)+1,EDATE(C2,9)+1))

G, Pay by:

=IF(F2="","",WORKDAY(F2+1,-1,Holidays!A$2:A))

H, Tax return due:

=IF(C2="","",LET(p,IF(D2="Short first tax period",MAX(C2,MAXIFS(C$2:C,A$2:A,A2,D$2:D,"First accounts")),C2),IF(p=EOMONTH(p,0),EOMONTH(p,12),EDATE(p,12))))

J, Check:

=IF(OR(E2="",I2=""),"",IF(E2=I2,"Matches","Check this date"))

Format E to I as dates. Here’s where each one comes from.

• Accounts: 9 months. A private company must file its accounts within 9 months of the end of its financial year (legislation.gov.uk). The catch is month-ends. If the year ends on the last day of a month, the deadline is the last day of the ninth month after it (legislation.gov.uk). So a 30 June year end is due on 31 March, not 30 March, and a 28 February year end is due on 30 November. That’s what the EOMONTH parts do.
• First accounts: the 21-month rule. If your first accounts cover more than 12 months, which is common because the first period runs from incorporation to your chosen year end, they’re due 9 months after the first anniversary of incorporation or 3 months after the period ends, whichever is later (legislation.gov.uk). That’s 21 months from the day you incorporated. A company incorporated on 14 March 2025 with first accounts to 31 March 2026 must file them by Monday 14 December 2026, not 31 December. Pick “First accounts” in column D for that row.
• Corporation Tax: 9 months and a day. GOV.UK puts it simply: “You must pay your Corporation Tax 9 months and 1 day after the end of your accounting period” (GOV.UK). HMRC’s manual adds the month-end rule: a period ending on the last day of a month is due on the first day of the tenth month after it (HMRC). So 31 December gives 1 October, and 31 March gives 1 January. This applies to taxable profits up to £1.5 million. Above that, you pay in instalments, and column F doesn’t apply.
• Pay by: the bank holiday trap. GOV.UK says that if the deadline falls on a weekend or bank holiday, you should “make sure your payment reaches HMRC on the last working day before it (unless you’re paying by Faster Payments using online or telephone banking)” (GOV.UK). Every 31 March year end hits this, because 1 January is always a bank holiday. Column G gives the last working day on or before the deadline. If you pay by Faster Payments, you have until the date in F, but G is the safer habit.
• Tax return: 12 months. “The deadline for your tax return is 12 months after the end of the accounting period it covers” (GOV.UK). For a 31 March year end, that’s the following 31 March. HMRC’s manual deals with February: a period ending on 28 February in the year before a leap year is due on 29 February, and one ending on 29 February is due on 28 February the next year (HMRC). So a 28 February 2027 year end gives a return due on Tuesday 29 February 2028. That’s what the EOMONTH part of column H does. If your year ends on 28 February just before a leap year, check the date with HMRC or your accountant.

The first year needs two rows. An accounting period for Corporation Tax “cannot be longer than 12 months”, and it may be different from your accounts in the year you set up the company (GOV.UK). So if your first accounts run for more than 12 months, HMRC splits them into two tax periods, each with its own payment date. Take the company incorporated on 14 March 2025, with first accounts to 31 March 2026. Its first tax period ends on 13 March 2026, so that Corporation Tax is due on Monday 14 December 2026. The second, short period ends on 31 March 2026, so that’s due on 1 January 2027. Put both in the sheet: a “Short first tax period” row with 13/03/2026 in column C, and a “First accounts” row with 31/03/2026. Use the dates in your HMRC letter or business tax account, not your own guess.

Here’s the part that surprises people: both tax returns are due on the same day. The law sets the filing date as the latest of several dates, including 12 months from the end of the period of account the return falls in (legislation.gov.uk). GOV.UK gives the same answer in its example of a year that’s been lengthened to 15 months: “file all returns by 31 March 2026” (GOV.UK). So for our example company, both returns are due on Wednesday 31 March 2027. Column H’s MAXIFS finds the first accounts row for the same company and works from the later of the two period ends. Make sure the Company name is spelt the same on both rows.

These tax dates assume a normal 12-month accounting period. The two rows above cover the usual long first year, but if your first period is shorter, or longer than the two rows allow, or you’ve changed your year end, check the dates by hand with your accountant or against HMRC’s guidance on accounting periods (GOV.UK). Changing your year end also moves your accounts deadline, unless you’re lengthening your company’s first financial year (GOV.UK).

Step 4: Add the confirmation statement tab

The confirmation statement has nothing to do with your year end. Each review period runs for 12 months from the day you incorporated, then from the day after your last confirmation date, and you have 14 days after it ends to file (legislation.gov.uk). Column D gives the last day of the review period, which is the latest confirmation date you can use. A period that starts on 1 March runs to the end of February, so it ends on 29 February in a leap year, and one that starts on 29 February ends on 28 February (legislation.gov.uk). Companies House says you can be fined up to £5,000, and your company may be struck off, if you don’t file (GOV.UK).

Add a tab called “Confirmation” with these headings:

D, Next confirmation date:

=IF(B2="","",LET(s,IF(C2="",B2,C2+1),IF(AND(MONTH(s)=2,DAY(s)=29),EDATE(s,12),EDATE(s,12)-1)))

E, File by:

=IF(D2="","",D2+14)

G, Check:

=IF(OR(E2="",F2=""),"",IF(E2=F2,"Matches","Check this date"))

For our 2019 example company, with a last confirmation date of 13 March 2026, that gives a next confirmation date of Saturday 13 March 2027 and a file-by date of Saturday 27 March 2027, which matches its register page. If yours says “Check this date”, believe the register and find out why: the usual reason is that someone filed early and picked a new date. Companies House allows that, and the next review period then starts the day after the new date (GOV.UK).

It costs £50 to file online or £110 on paper (GOV.UK). You pay the fee with the first statement in each 12-month payment period, and Companies House says the payment period is separate from the review period (GOV.UK).

Before you file, check every director has verified their identity. Companies House says: “We will not accept your company’s confirmation statement until all directors have verified their identity” (GOV.UK). If you haven’t done yours yet, do it well before the file-by date. Our Companies House ID verification guide explains the personal code you’ll be asked for.

Step 5: Add a Due soon tab and the colours

Add a tab called “Due soon” and put this in A1. It lists every deadline in the next 90 days, soonest first:

=IFERROR(ARRAYFORMULA(LET(all,{Deadlines!A2:A,IF(Deadlines!A2:A="","","Accounts to Companies House"),Deadlines!E2:E;Deadlines!A2:A,IF(Deadlines!A2:A="","","Pay Corporation Tax"),Deadlines!G2:G;Deadlines!A2:A,IF(Deadlines!A2:A="","","Company Tax Return to HMRC"),Deadlines!H2:H;Confirmation!A2:A,IF(Confirmation!A2:A="","","File confirmation statement"),Confirmation!E2:E},d,INDEX(all,0,3),SORT(FILTER(all,ISNUMBER(d),d>=TODAY(),d<=TODAY()+90),3,TRUE))),"Nothing due in the next 90 days")

Format column C of this tab as a date, or the dates show as numbers.

Then the colours. On the Deadlines tab, select E2:H, go to Format › Conditional formatting, choose Custom formula is and add two rules, red first:

• Red: =AND(ISNUMBER(E2),$K2="",E2-TODAY()<=30), for anything due within 30 days that you haven’t marked done.
• Amber: =AND(ISNUMBER(E2),$K2="",E2-TODAY()<=60), for anything due within 60 days.

Do the same on the Confirmation tab for E2:E, using $H2 in place of $K2.

Step 6: Turn on the free reminders

The sheet only helps if you open it, so add two nudges that come to you.

First, Companies House email reminders. The service is free, and Companies House says it’s “no longer sending paper reminders by post” (GOV.UK). Sign in to the Companies House online filing service, select “Activate e reminders” from your company overview screen and add up to 4 email addresses: yours, plus your accountant’s if you have one.

Second, the calendar. Paste Part 3 of the prompt’s answer into Google Calendar as all-day events, and add notifications 60, 30 and 7 days before each one. For the Corporation Tax payment, use the date in column G, not F.

While you’re there, check you can file. Filing online, whether through Companies House’s own service or commercial software, needs the company authentication code: a 6-character code Companies House posts to your registered office, which “can take up to 10 working days to arrive”. It’s different from the personal code a director gets when they verify their identity (GOV.UK). If you can’t find it, ask for it now, not in December.

Step 7: Check the dates once a quarter

Put a 5-minute event in your calendar on the first Monday of each quarter. Open the register page, copy the dates, run the prompt again and compare with the sheet. Anything that says “Check this date” gets sorted that day. When you file or pay, put the date in Done or Filed on, and add next year’s row.

If you have an accountant, the quarterly check is when you ask two questions: have you got everything you need from me, and when will it be filed? GOV.UK is clear that a professional can file for you, “but you’re still legally responsible for your company’s accounts, records and performance” (GOV.UK). It also lists “it was your accountant’s (or anybody else’s) fault” as a reason an appeal against a late filing penalty may not succeed, along with “these were your first accounts” (GOV.UK).

The copy-paste prompt

Paste the text after “Text:” in place of [paste].

You help the director of a small UK private limited company keep track of its
filing dates. I will paste text copied from the company's page on the
Companies House register and, if I have them, from the company's HMRC business
tax account or HMRC letters. Use ONLY what is written in the text: never guess
a date, and do not work out or add any date that is not printed. PART 1,
TABLE: one row per date printed in the text, with columns Company, What it is
(for example Next accounts made up to, Accounts due by, Next statement date,
Confirmation statement due by, Corporation Tax accounting period end,
Corporation Tax payment due, Company Tax Return due), Date, and Source
(Companies House or HMRC). Write dates as DD/MM/YYYY so I can paste the rows
into Google Sheets. PART 2, GAPS: one line for anything missing or unclear,
such as no HMRC dates in the text, a filing marked overdue, or two dates for
the same thing that don't match. If nothing is missing, say so. PART 3,
CALENDAR: for each due date in Part 1, one line I can use as a calendar event
title, in the form Company: what is due, date (source). RULES: British
English, plain and direct. Do not give tax or legal advice and do not mention
penalties. If the text is cut off or doesn't say something you need, add a
short note in brackets saying in plain words what to check, for example (check
this date on the Companies House register). Text: [paste]

What can go wrong?

• Filing late because you’re filing it yourself for the first time. HMRC’s free service closed on 31 March 2026, and GOV.UK says you should now file the Company Tax Return “using commercial software” (GOV.UK). HMRC publishes a list of suppliers (GOV.UK). Pick one at least a month before the return is due. Companies House still has its own accounts service for now, but “from 1 April 2028, all companies must file their accounts using commercial software” (GOV.UK).
• Late penalties that grow. For accounts, a private company pays £150 up to a month late, £375 at 1 to 3 months, £750 at 3 to 6 months and £1,500 after that, and “the penalty is doubled if your accounts are late 2 years in a row” (GOV.UK). For the tax return, it’s £200 straight away, another £200 at 3 months, then a percentage of any unpaid tax at 6 and 12 months. “If your tax return is late 3 times in a row, the £200 penalties are increased to £1000 each” (GOV.UK). Late tax also runs up interest (GOV.UK).
• Changing your year end. If you shorten or lengthen your accounting reference date, the accounts deadline and the tax periods both change. Update column C and the row types the day the change is accepted, and check the new dates on the register and with HMRC. The formulas don’t cover the 3-month rule for a shortened period, so trust the register over the sheet that year.
• Weekends. Column G moves the payment back to a working day. The other columns don’t move, so if a filing deadline falls on a Saturday, file by the Friday.
• Bigger profits. If your taxable profits are over £1.5 million, Corporation Tax is paid in instalments (GOV.UK), and columns F and G don’t apply.
• Trusting the prompt. It’s told to copy only printed dates, but AI tools can misread a table or drop a line. Check every row against the register and your HMRC account before you rely on it. The Check columns are there to catch exactly that.
• This isn’t tax advice. The sheet tracks dates. What you owe, and how to pay less of it legally, is a question for an accountant.

A deadline sheet stops the fines. Getting paid on time keeps the tax money in the account: our unpaid invoice chaser does that part. And if a brown envelope from HMRC lands anyway, our guide to summarising HMRC letters and drafting a reply helps you answer it. One practical automation like this, with the £ and the hours it saves, lands in your inbox every Friday if you join our free email.

Frequently asked questions

Sources

1. GOV.UK: Prepare annual accounts for a private limited company (including late filing penalties)
2. GOV.UK: File your company's annual accounts with Companies House
3. GOV.UK (Companies House): Using software to file your company's information (25 September 2026)
4. GOV.UK (HMRC): Closure of the service to file your company accounts and tax return
5. GOV.UK: Pay your Corporation Tax bill
6. GOV.UK: Company Tax Returns (deadlines and penalties)
7. GOV.UK: Accounting periods for Corporation Tax
8. GOV.UK: Change your company's year end
9. HMRC Company Taxation Manual CTM01800: Corporation Tax due date of payment
10. GOV.UK (Companies House): Filing your company's confirmation statement
11. GOV.UK (Companies House): Registering for email reminders
12. GOV.UK (Companies House): Company authentication codes for online filing
13. GOV.UK: UK bank holidays
14. legislation.gov.uk: Companies Act 2006, section 442 (period for filing accounts)
15. legislation.gov.uk: Companies Act 2006, section 443 (calculation of period allowed)
16. legislation.gov.uk: Companies Act 2006, section 853A (duty to deliver confirmation statements)
17. legislation.gov.uk: Finance Act 1998, Schedule 18, paragraph 14 (filing date for a company tax return)
18. HMRC Company Taxation Manual CTM93040: filing date, 12 months from the end of the return period

This guide is general information, not legal, tax or financial advice. Tool prices and screens change; we re-check every guide regularly. Spotted something out of date? Tell us and we’ll fix it.