UK SaaS Companies House confirmation statement 2026: the Form CS01 walkthrough for solo founders, PSC, and the dormant company route

Every UK limited company files a CS01 every 12 months. Pre-revenue dormant SaaS, side-project Ltd you incorporated last June, fully trading Stripe-connected product -- all of them owe Companies House a CS01 on the anniversary of incorporation.

Most indie founders miss the deadline once and panic. They shouldn't. The fee is GBP 13 online -- versus GBP 40 paper that no indie actually uses -- with a 14-day grace window after the confirmation date. The filing takes 10 minutes if nothing changed, 20 if PSC or shareholder data needs updating.

This walkthrough makes the CS01 a Tuesday-morning admin task. We cover the seven sections, the PSC mechanics that trip up indies after a SAFE round, the dormant-company route at GBP 13/year, and how the CS01 fits with HMRC corporation tax, PAYE and VAT. The free IdeaStack weekly report covers the wider UK SaaS regulatory stack -- link at the end.

What the CS01 actually is (and isn't)

The CS01 is a confirmation statement. You are not filing a tax return. You are not filing accounts. You are not telling HMRC anything. You are telling Companies House that the details on your public record are still accurate.

It replaced the old "annual return" in 2016 and is officially Form CS01. WebFiling calls it "Confirmation Statement". Same thing.

What the CS01 is not:

• Not a tax return. Corporation tax is HMRC's CT600 -- different agency, different deadline.
• Not company accounts. Annual accounts (AA01/AA02) are a separate filing 9 months after your accounting reference date.
• Not optional for dormant companies. A dormant Ltd that has never made a sale still owes a CS01 every year.
• Not a security check. Companies House publishes what you say on Find-and-Update for the world to see. Accuracy is on you.

The job of a CS01 is to keep the public record current: who runs the company, who owns it, where it's based, what it does.

The seven things you confirm

The CS01 walks through seven sections. Some are pre-populated from the register. Some need attention. Here's the lot:

#	Section	What you check	Update mid-year?
1	Registered office address	Real UK address (home, registered office service, accountant)	Yes -- file AD01 immediately
2	Directors and secretary	Names, DOB, service address; secretary is rare for SaaS	Yes -- file AP01/TM01/CH01
3	Shareholders and shareholdings	Names and number of shares held by each	Reflected via SH01 share allotments
4	SIC codes	What the company does -- e.g. 62012 = business and domestic software development	Only at CS01
5	Statement of capital	Number of shares issued, nominal value, currency	Reflected via SH01
6	People with Significant Control (PSC)	Anyone with >25% shares, voting rights or significant influence	Yes -- file PSC01/PSC02/PSC04/PSC07
7	Single contact email	Mandatory since 2024 -- one email for the company	Update inside the CS01

Notes worth highlighting:

• SIC codes. Most UK SaaS founders should use 62012 (business and domestic software development), not 62020 (IT consultancy) -- that's for consultants who code for clients, not product builders. Up to four allowed.
• Email. Since March 2024, every UK company must register a single contact email. It isn't published, but Companies House uses it for the 28-day reminder. Use one you read.
• Service address vs home address. Directors and PSCs can use a service address for the public record while home address sits on a private Companies House file. Get this right at incorporation.

The PSC section -- where indies trip up

This is the section that catches solo founders and small co-founder teams. PSC stands for People with Significant Control, and the rules are precise. You're a PSC if you tick any of these boxes:

• You hold more than 25% of the shares
• You hold more than 25% of the voting rights
• You have the right to appoint or remove a majority of directors
• You exercise -- or have the right to exercise -- significant influence or control

The "more than 25%" is the rule that matters for almost every indie SaaS. Let's run through the typical scenarios:

Sole founder, 100% shareholder. You are the PSC. Your CS01 needs full name, DOB, nationality and a service address. Home address stays private; service address is public.

50/50 co-founders. Both are PSCs. Two entries, two service addresses, two DOBs. Tick "ownership of shares -- more than 25% but not more than 50%" for each.

60/40 split. Both are PSCs (40% is above the 25% floor -- the most common indie misunderstanding).

80/10/10 split. Only the 80% holder is a PSC. The 10% holders are shareholders only.

SAFE-converted seed round adding investor at 18%. Not a PSC. Unless they have appointment or veto rights in the SHA, in which case they may qualify under "significant influence or control". Read the SHA.

Co-founder vests through 25% mid-year. File PSC01 (new PSC) or PSC04 (change of nature) within 14 days. Don't wait for the CS01.

Common indie errors:

1. Adding a new PSC at the CS01 when the change happened months ago. The PSC01 should have been filed within 14 days.
2. Listing a 24% co-founder as a PSC when they aren't one. Don't over-disclose.
3. Forgetting to update PSC details after a name, address or nationality change. File a PSC04.
4. Leaving a home address public after a house move. Use a service address.

The dormant company route for pre-launch indies

A company is "dormant" for Companies House purposes if it has had no significant accounting transactions during the financial year. The legal phrase is "no significant transactions other than those permitted by the Companies Act". In practice, this means:

Allowed in a dormant year:

• Paying for shares when the company is incorporated (capital event, not a transaction)
• Paying the Companies House CS01 fee (GBP 13 -- treated as administrative)
• Paying the Companies House late filing penalty if you missed a filing (also administrative)
• Paying for a .co.uk domain registration if treated as a capital asset
• Allotting new shares (capital event)
• Paying for a registered office service if structured correctly (some accountants allow this -- check)

Disqualifies dormant status:

• Issuing your first invoice to a customer
• Paying a Vercel/Supabase/Stripe bill against the company (that's a deductible business expense -- the company is trading)
• Running PAYE -- even GBP 1 of salary
• Paying yourself a director's loan or dividend
• Paying for any service consumed by the business (accounting software, design tools, hosting)

Annual cost of a fully dormant Ltd:

• CS01 confirmation statement: GBP 13
• Dormant accounts (Form AA02): GBP 0
• Corporation tax: GBP 0 (no profit, no liability -- but you may still need to tell HMRC the company is dormant)
• Total: GBP 13/year

Why indies use the dormant route:

1. Name protection. Companies House is first-come-first-served. Incorporate the name 12 months before you launch, and no one else can grab "AcmeSaaS Ltd".
2. Domain pairing. Claim the .co.uk and the company at the same time, hold both for under GBP 30/year combined, ship when you're ready.
3. Company history. Lenders, payment processors and B2B buyers look at incorporation date. A 2-year-old company looks more credible than a 2-week-old one when you finally apply for a Stripe account, business bank account, or B2B procurement onboarding.
4. Optionality. You can start trading whenever you decide -- just notify HMRC within 3 months of starting trading and switch from dormant accounts to micro-entity accounts the next year.

The dormant route is genuinely the cheapest legitimate way to hold a UK company name. Just make sure you don't accidentally trade. The first Vercel bill paid by the company card is the trigger.

Filing the CS01 in 10 minutes

Here is the exact sequence on WebFiling:

Step 1 -- Get your authentication code. Every UK company has a 6-character alphanumeric authentication code. It was emailed to you at incorporation, or it lives in the incorporation pack from your formation agent. Lost it? Companies House will reissue by post in 5 working days to the registered office. Don't leave this until the day before the deadline.

Step 2 -- Login to WebFiling. Go to the Companies House WebFiling service. Enter your company number (the 8-digit number on your incorporation certificate) and your authentication code. Two-factor sign-in is via the email on file.

Step 3 -- Click "File a confirmation statement". WebFiling pre-populates the seven sections from the current public record. You will tick a confirmation for each section: confirm or update. Most years, everything is tick-confirm, tick-confirm.

Step 4 -- Update what's changed. SIC codes are updated inside the CS01. Email is updated inside the CS01. Statement of capital can be updated. PSC and director changes should already have been filed mid-year via the relevant form -- if they weren't, you'll be prompted to file the underlying form first before continuing.

Step 5 -- Pay GBP 13 by card. WebFiling takes Visa and Mastercard. The receipt arrives by email within minutes. You'll see the filing on Find-and-Update Company Information within 24 hours.

Step 6 -- Diary the next one. Add the next confirmation date to your calendar with a 28-day-before reminder. Companies House will email you anyway, but don't rely on it -- the reminder lands in the company contact email which may be a forwarder you forget about.

A note on WebFiling versus the API. The Companies House API exists and supports CS01 submissions, but it's intended for accountants and formation agents who batch-file for many clients. As a solo indie, use WebFiling. Don't burn 4 hours of build time on an API integration to save 10 minutes once a year.

The 14-day window -- and what happens if you miss it

The mechanics:

• Confirmation date = anniversary of incorporation, OR anniversary of your last CS01 filing if you filed early in a previous year.
• Filing deadline = confirmation date + 14 days. Strict. Day 15 is late.
• Reminder = Companies House sends an email 28 days before the confirmation date to your registered company email.

If you miss the 14-day window:

• The company gets a "default" mark on its Find-and-Update record. Visible to anyone -- lenders, suppliers, customers checking you out.
• Companies House will write again. If you keep ignoring them, the company is proposed for strike-off (dissolution).
• Strike-off proposal is published in the London Gazette. After 2 months in the Gazette with no objection, the company is dissolved. Done.
• Officers (directors) of a struck-off company can be liable. The company assets pass to the Crown -- bona vacantia. Bank balance gone.

Restoration if you've been struck off:

• Administrative restoration (within 6 years of strike-off, Crown application): GBP 100 + outstanding filing fees + a written application to Companies House. Available only if the company was carrying on business at strike-off.
• Court order restoration (after 6 years or for non-trading companies): more expensive, more time, lawyer territory.

Practical tip: file early. WebFiling lets you file a confirmation statement at any point in the confirmation period, not just within the 14-day grace. Filing early resets the next confirmation date forward to the new filing date. Useful if you want to align your CS01 with the start of a quarter, your accounting year, or any anchor date that's easier to remember than "23 June at 11pm because that's when you incorporated in 2023".

What to update WHEN -- mid-year vs CS01

Important distinction. Some changes need filing immediately mid-year; some get rolled up into the CS01.

File mid-year (separate forms, within 14 days of the change):

• Registered office change -- AD01
• Director appointment -- AP01
• Director resignation -- TM01
• Director name/address change -- CH01
• Share allotment -- SH01
• New PSC -- PSC01
• PSC ceases -- PSC07
• PSC change of nature -- PSC04

Update only at CS01:

• SIC codes (the company's listed activities)
• Statement of capital -- though if you allot new shares mid-year via SH01, that's reflected
• The single contact email (since 2024)

Common indie mistake: waiting for the CS01 to add a new PSC who crossed 25% in October. Wrong. The PSC01 is owed within 14 days of the change. The CS01 confirms what's already on file.

Why it matters: Companies House won't reject the CS01 if you do the underlying filing first. But if you try to confirm a PSC list that doesn't match the actual current ownership, you'll be filing a false statement -- which is technically a criminal offence under the Companies Act. Reality check: enforcement is light for small honest mistakes, but the risk is non-zero, and lenders/diligence buyers do read the filing history.

The CS01 vs Corporation Tax vs PAYE timeline

The CS01 sits alongside several other UK filing obligations. They have nothing to do with each other in terms of deadlines, but they share the same company. Diary them separately.

Filing	When	Where	Cost
CS01 confirmation statement	Annually, on incorporation anniversary, 14-day grace	Companies House	GBP 13
Annual accounts (AA01 or AA02)	9 months after accounting reference date	Companies House	GBP 0
HMRC notify of trading start	Within 3 months of starting to trade	HMRC	GBP 0
Corporation tax return CT600	12 months after end of accounting period	HMRC	GBP 0
Corporation tax payment	9 months and 1 day after end of accounting period	HMRC	varies
PAYE registration	Before first payday	HMRC	GBP 0
PAYE RTI submissions	Each payday	HMRC	GBP 0
VAT registration	Mandatory if 12-month rolling turnover hits GBP 90,000 (2024 threshold)	HMRC	GBP 0

A few cross-cuts that catch indies:

• Corporation tax payment is due before the return is due. You file the CT600 within 12 months but pay within 9 months and 1 day. If you over-pay, you get a refund.
• PAYE applies even if you pay yourself GBP 1 of salary. If the company employs no one and the founder takes only dividends, no PAYE is needed.
• VAT below GBP 90k is voluntary. Some B2B SaaS founders register early to reclaim VAT on Vercel/SaaS tooling, but that means charging VAT on customer invoices -- check whether your customers can reclaim it before you decide.
• The CS01 is independent of all of the above. A dormant company with no HMRC dealings still owes a CS01 every 12 months.

Five common UK SaaS indie CS01 mistakes

1. Missing the 14-day window because no one diaried the anniversary. The Companies House email reminder goes to the contact email on file -- which is often a forwarder, an old founder address, or a VA's inbox that nobody monitors. Diary the anniversary in the calendar you actually use, with a 28-day-before alert.

2. Forgetting to update PSC after a co-founder vests through 25% mid-year. Vesting schedules and SAFE conversions both trigger PSC changes. File the PSC01 within 14 days of the change, don't wait for the CS01.

3. Wrong SIC code. SaaS founders default-pick 62020 (IT consultancy) when they should use 62012 (business and domestic software development). 62012 is the correct code for product builders. 62020 is for service-based dev shops billing time.

4. Filing dormant accounts when the company has actually started trading. The first Vercel bill paid by the company card is the trigger. From that point, the company is trading -- even if revenue is zero. Switch to micro-entity accounts (AA01) at the next accounting reference date and notify HMRC within 3 months of starting trading.

5. Using a home address as registered office and forgetting it's public on Find-and-Update. Anyone can search your company name and see the address. Risk: scam mail (fake "Companies House" demands), unsolicited sales, harassment. Use a registered office service from day one -- they're GBP 30-100/year. Cheaper than the hassle of trying to suppress your home address from the register later.

30-minute ship-it for the first CS01

A pre-flight checklist. Block 30 minutes on a Tuesday morning, work through this top to bottom, done.

• 0:00 -- Locate company authentication code. It's in your incorporation pack or the email Companies House sent at incorporation. If you've lost it, request a reissue by post (5 working days). Don't start the rest of this until you have it.
• 0:05 -- Login to WebFiling. Company number + authentication code. Set up two-factor on the email on file.
• 0:10 -- Click "Confirmation Statement" and walk through each section. Confirm or update. The seven sections take roughly 1 minute each if nothing has changed, longer if PSC or shareholder data needs work.
• 0:20 -- Pay GBP 13 by card. Save the email confirmation as a PDF in your "company admin" folder.
• 0:25 -- Diary next year's CS01. Calendar event on the new confirmation date with a 28-day-before alert. Note the confirmation date in your "company admin" folder so you don't have to look it up next year.
• 0:30 -- Done. Make a coffee. The next 12 months of your company's existence are bought and paid for.

What happens if you sell or close the company

Two clean exits, both bypass the next CS01 if you act before the anniversary.

Voluntary strike-off (DS01):

• File DS01 with Companies House (GBP 8 fee). Available if the company has not traded or changed name in the last 3 months.
• Companies House publishes a notice in the London Gazette. After 2 months in the Gazette with no objection, the company is dissolved.
• If your CS01 anniversary falls within the 2-month Gazette window, you don't need to file the CS01 -- the company will be gone before the next confirmation date.
• Caveat: you must distribute or transfer all assets first. Anything left in the company at strike-off becomes Crown property under bona vacantia.

Sale of company (share transfer):

• Stock transfer form (J30) signed by buyer and seller. Stamp duty: 0.5% of consideration, GBP 5 minimum, rounded up to nearest GBP 5. Payable to HMRC.
• Update Companies House: the transfer is reflected at the next CS01, but if shareholders crossed the 25% threshold, file PSC01/PSC07 within 14 days.
• Director changes (you resign, buyer's directors appointed) -- file TM01 and AP01.

Either route, the next CS01 either becomes the buyer's problem or is moot because the company no longer exists. Just don't sit on a half-done strike-off through your CS01 anniversary -- you'll owe both the GBP 13 and the strike-off fee.

Cross-link callouts

This post sits in a wider UK SaaS founder operations stack. If you're working through the lot:

• 2026-04-28-uk-saas-first-hire-stripe-companies-house-pension-2026 -- the first-hire compliance thread, including how PSC and Companies House obligations change when you hire.
• 2026-04-25-uk-saas-pricing-gbp-tiers-2026 -- pricing tiers and the VAT registration trigger interaction.
• 2026-04-26-uk-saas-legal-pages-template-2026 -- the wider UK legal stack (terms, privacy, cookies, data processing).
• 2026-04-29-uk-indie-hacker-founder-taxes-director-loan-dividend-mtd-itsa-2026 -- the founder taxes companion piece (today's other post).

FAQs

Do I need to file a CS01 if my company is dormant?

Yes. A dormant Ltd files the same CS01 as a trading Ltd, on the same anniversary, for the same GBP 13 fee. Dormant status affects HMRC corporation tax obligations and the type of accounts you file (AA02 instead of AA01), but the CS01 is unaffected. The CS01 is about the company's existence on the public register, not about whether it's trading.

What is a PSC and am I one?

A PSC -- Person with Significant Control -- is anyone who owns more than 25% of the shares, holds more than 25% of the voting rights, has the right to appoint or remove a majority of directors, or otherwise exercises significant influence or control. If you're a sole founder owning 100% of your company, you are the PSC. If you and a co-founder split 50/50, you are both PSCs. If a third party owns 24% and has no special rights, they are not a PSC. The threshold is "more than 25%", and 25% itself isn't a PSC trigger -- it's strictly above.

I forgot to update my PSC mid-year -- can I do it on the CS01?

The CS01 will let you confirm a PSC list that's accurate as of the confirmation date, but the underlying change should have been filed within 14 days of when it happened, via PSC01 (new PSC), PSC04 (change in nature of control), or PSC07 (PSC ceased). File the underlying form first, then file the CS01. Companies House won't typically chase a small late filing on PSC, but the obligation is on you to file each change as it happens, not in batches at year-end.

I missed my 14-day window by 3 days -- am I in trouble?

Almost certainly not. File it now via WebFiling, pay the GBP 13. Companies House will mark the filing as late on Find-and-Update (a small visible default flag on the public record) but won't pursue strike-off for a 3-day delay on a single CS01. Strike-off proceedings start after multiple defaults or sustained non-filing -- typically months, not days. Don't ignore future deadlines, but a one-off 3-day late filing is a paperwork blip, not a crisis.

Can I file the CS01 from outside the UK?

Yes. WebFiling is online, accessible from anywhere with an internet connection and a UK card for the GBP 13 fee. Your company must still have a UK registered office (a real UK address), but the founder/director can be filing from a beach in Lisbon. Companies House doesn't care where you are -- they care that the registered office is a UK address that can receive post.

Key takeaways

• The CS01 is a confirmation statement, not a tax return -- GBP 13 online, 14-day grace, file via Companies House WebFiling once a year on the anniversary of incorporation.
• All UK companies file a CS01, including dormant ones -- it's the company-existence check, separate from corporation tax, PAYE and VAT.
• PSC means anyone with more than 25% shares, voting rights or significant influence -- file PSC01/PSC04/PSC07 within 14 days of any change, not at year-end.
• The dormant company route costs roughly GBP 13/year and is the cheapest way to hold a name + .co.uk pair pre-launch -- but the first Vercel bill paid by the company kills dormant status.
• Diary four separate UK deadlines -- CS01 (Companies House), accounts (Companies House), CT600 (HMRC), PAYE/RTI (HMRC) -- they share a company but nothing else.

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