- Companies
- Civil engineering
- London
- N21 Building Ltd
N21 Building Ltd
- Company number
- 04808124
- Incorporated
- 23 Jun 200323 years trading
- Registered office
- 109 Wades Hill, Winchmore Hill, London, N21 1AP
- Nature of business
- Construction of other civil engineering projects n.e.c.
N21 Building Ltd is a 23-year-old private limited company registered in London, company number 04808124, one of 1,853 civil engineering contractors in London. Its next accounts are due at Companies House on 25 June 2027, and the CT600 for the period to 25 September 2026 is due at HMRC on 25 September 2027.
Key dates
Worked out from the year end and filing history on the Companies House register.
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Finances
From each year's balance sheet filed at Companies House. Small companies do not have to publish turnover or profit, so these are balance sheet figures.
- Net assets up £1,445 (+19.3%) on the year before, to £8,944.
- Net assets rose in 4 of 9 year-on-year comparisons on record.
- Current assets of £162K against £162K owed within a year: 1.0 times cover.
- 7 employees on average, down from 8 the year before.
- Balance sheets on record for 10 years, 2017 to 2025.
Net assets by year
| Year end | Net assets | Cash | Current assets | Owed within a year | Employees |
|---|---|---|---|---|---|
| 30 Sep 2025 | £8,944 | £162K | £162K | 7 | |
| 30 Sep 2024 | £7,499 | £212K | £208K | 8 | |
| 25 Sep 2024 | £7,499 | £212K | £208K | 7 | |
| 25 Sep 2023 | £13K | £207K | £197K | 7 | |
| 25 Sep 2022 | £2,893 | £152K | £134K | 7 | |
| 25 Sep 2021 | £2,744 | £160K | £93K | 7 | |
| 30 Sep 2020 | £2,026 | £123K | £125K | 7 | |
| 30 Sep 2019 | £9,121 | £99K | £96K | ||
| 30 Sep 2018 | £12K | £121K | £107K | ||
| 30 Sep 2017 | £33K | £146K | £111K |
Where N21 Building Ltd is registered
The registered office is in London (N21), in the Enfield local authority area, London. Show N21 1AP on a map.
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What happens if N21 Building 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 25 June 2027.
| Companies House | Accounts delivered | Penalty |
|---|---|---|
| Up to 1 month late | 26 Jun 2027 to 25 Jul 2027 | £150 |
| 1 to 3 months late | 26 Jul 2027 to 25 Sep 2027 | £375 |
| 3 to 6 months late | 26 Sep 2027 to 25 Dec 2027 | £750 |
| More than 6 months late | From 26 Dec 2027 | £1,500 |
Penalties double if the accounts were also late the year before.
| HMRC (CT600) | From | Penalty |
|---|---|---|
| 1 day late | 26 Sep 2027 | £200 |
| 3 months late | 25 Dec 2027 | another £200 |
| 6 months late | 25 Mar 2028 | HMRC estimates the tax and adds 10% of the unpaid tax |
| 12 months late | 25 Sep 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
- 04808124
- Status
- Active
- Company type
- Private limited company
- Incorporated
- 23 June 2003 (23 years ago)
- Registered office
- 109 Wades Hill, Winchmore Hill, London, N21 1AP
- Nature of business
- Construction of other civil engineering projects n.e.c. (SIC 42990)
- Year end
- 25 September (accounting reference date)
- Accounts type
- Micro-entity
- Last accounts made up to
- 30 September 2025
- Last confirmation statement
- 23 June 2026
Filing notes for civil engineering contractors
Civil engineering contractors usually carry plant and machinery, so capital allowances (the annual investment allowance and the main pool) do much of the work in the corporation tax computation.
Similar companies in London
Other active civil engineering contractors registered in London.
- Na General Construction Ltd2013
- Nadia and Co Limited2014
- Nadiifo Service Limited2025
- Nakfa Solution Ltd2025
- Nambuild Limited2014
- Naseby Energy Holdings Limited2024
- Naseby One Limited2025
- Nastaran Electricco Ltd.2015
All civil engineering contractors in London · All trades in London · Civil engineering across the UK
Frequently asked questions
When are N21 Building Ltd's accounts due?
N21 Building Ltd's next accounts are due at Companies House by 25 June 2027 (in 255 days), covering the period to 25 September 2026.
When is N21 Building Ltd's CT600 due?
The CT600 for the period to 25 September 2026 is due at HMRC by 25 September 2027, 12 months after the period end. The corporation tax itself is payable earlier, by 26 June 2027.
Is N21 Building Ltd still trading?
N21 Building 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 N21 Building Ltd do?
N21 Building Ltd is registered under Construction of other civil engineering projects n.e.c. (SIC 42990).
How old is N21 Building Ltd?
N21 Building Ltd was incorporated on 23 June 2003, 23 years ago.
What is the penalty if N21 Building 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 N21 Building 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.