- Companies
- Finishing trades
- London
- Si Design Project Ltd
Si Design Project Ltd
- Company number
- 15548311
- Incorporated
- 8 Mar 20242 years trading
- Registered office
- 35 Grafton Way, London, W1T 5DB
- Nature of business
- Other building completion and finishing; Retail of furniture, lighting, and similar (not musical instruments or scores) in specialised store; specialised design activities; Other service activities n.e.c.
Si Design Project Ltd is a 2-year-old private limited company registered in London, company number 15548311, one of 3,947 building finishing companies in London. Its next accounts are due at Companies House on 30 November 2026, and the CT600 for the period to 28 February 2026 is due at HMRC on 28 February 2027.
Key dates
Worked out from the year end and filing history on the Companies House register.
Is this your company?
File the accounts to Companies House and the CT600 to HMRC yourself with A.X.E.L Filing. One set of questions, both filings, £49 flat. No accountant, no subscription.
File for Si Design Project LtdOr get a reminder before each deadline
Free. We email you 60, 30, 14, 7 and 1 days before the accounts, CT600 and confirmation statement are due. Unsubscribe in one click.
Financial snapshot, 2025
From the balance sheet at 28 February 2025, as filed at Companies House.
Where Si Design Project Ltd is registered
The registered office is in London (W1T), in the Camden local authority area, London. Show W1T 5DB on a map.
Other trade companies in W1T
- Preschools Cleaning Company LtdCleaning companies
- Northheat Plumbing & Heating LtdPlumbers and heating engineers
- Leuk Lift Engineering UK LtdMachinery repair and installation
- Az Maintenance Services LimitedFinishing trades
- Braintree Property Service LtdBuilders
- Nona Construction & Retrofit LtdBuilders
- Denvav LimitedBuilders
- Marshall Roofing Services LtdRoofers
Shared registered office
73 companies on our pages use this registered office address. An address shared this widely is usually an accountant's office or a company formation agent's service address, not where the business trades from.
What happens if Si Design Project Ltd files late
Companies House charges an automatic penalty the day after the deadline, and it rises the longer the accounts are late. These are the dates for this company's accounts due on 30 November 2026.
| Companies House | Accounts delivered | Penalty |
|---|---|---|
| Up to 1 month late | 1 Dec 2026 to 31 Dec 2026 | £150 |
| 1 to 3 months late | 1 Jan 2027 to 28 Feb 2027 | £375 |
| 3 to 6 months late | 1 Mar 2027 to 31 May 2027 | £750 |
| More than 6 months late | From 1 Jun 2027 | £1,500 |
Penalties double if the accounts were also late the year before.
| HMRC (CT600) | From | Penalty |
|---|---|---|
| 1 day late | 1 Mar 2027 | £200 |
| 3 months late | 28 May 2027 | another £200 |
| 6 months late | 28 Aug 2027 | HMRC estimates the tax and adds 10% of the unpaid tax |
| 12 months late | 28 Feb 2028 | another 10% of any unpaid tax |
For returns filed on or after 1 April 2026. Late three times in a row and the £200 penalties become £1,000 each.
Company details
As held on the Companies House register.
- Company number
- 15548311
- Status
- Active
- Company type
- Private limited company
- Incorporated
- 8 March 2024 (2 years ago)
- Registered office
- 35 Grafton Way, London, W1T 5DB
- Nature of business
- Other building completion and finishing (SIC 43390)
Retail of furniture, lighting, and similar (not musical instruments or scores) in specialised store (SIC 47599)
specialised design activities (SIC 74100)
Other service activities n.e.c. (SIC 96090) - Year end
- 28 February (accounting reference date)
- Accounts type
- Micro-entity
- Last accounts made up to
- 28 February 2025
- Last confirmation statement
- 7 March 2026
Filing notes for building finishing companies
Finishing trade companies cover a wide range of work. Most are micro-entities with simple accounts and a straightforward CT600.
Similar companies in London
Other active building finishing companies registered in London.
- Sibs Consulting Limited2014
- Sienna Maintenance Ltd2024
- Sigi Solution Limited2018
- Signature Group Enterprises Limited2026
- Silentwave Group Ltd2011
- Silicon Capital Ltd2014
- Sim2Sim Limited2015
- Simabuild Ltd2011
All building finishing companies in London · All trades in London · Finishing trades across the UK
Frequently asked questions
When are Si Design Project Ltd's accounts due?
Si Design Project Ltd's next accounts are due at Companies House by 30 November 2026 (in 49 days), covering the period to 28 February 2026.
When is Si Design Project Ltd's CT600 due?
The CT600 for the period to 28 February 2026 is due at HMRC by 28 February 2027, 12 months after the period end. The corporation tax itself is payable earlier, by 1 December 2026.
Is Si Design Project Ltd still trading?
Si Design Project Ltd is listed as active on the Companies House register as of 1 Oct 2026. Active means it has not been dissolved or entered insolvency; it does not show whether it is currently taking on work.
What does Si Design Project Ltd do?
Si Design Project Ltd is registered under Other building completion and finishing (SIC 43390); Retail of furniture, lighting, and similar (not musical instruments or scores) in specialised store (SIC 47599); specialised design activities (SIC 74100); Other service activities n.e.c. (SIC 96090).
How old is Si Design Project Ltd?
Si Design Project Ltd was incorporated on 8 March 2024, 2 years ago.
What is the penalty if Si Design Project Ltd files its accounts late?
Companies House charges £150 if the accounts are up to 1 month late, £375 up to 3 months, £750 up to 6 months and £1,500 after that, doubled if the previous year's accounts were also late. HMRC charges £200 for a CT600 filed a day late and another £200 at 3 months.
Official records
View Si Design Project Ltd on Companies House for filed documents, officers and the full history.
Based on the Companies House register (snapshot 1 Oct 2026). Deadlines are worked out from the register and assume a standard accounting period; a change of year end or a short period moves them. This page is general information, not tax or accountancy advice.