- Companies
- Specialist contractors
- London
- Constantin Mainsolution Ltd
Constantin Mainsolution Ltd
- Company number
- 16611030
- Incorporated
- 29 Jul 20251 year trading
- Registered office
- Flat 4, 12A Baronet Grove, London, N17 0LX
- Nature of business
- Other specialised construction activities n.e.c.; Landscape service activities
Constantin Mainsolution Ltd is a 1-year-old private limited company registered in London, company number 16611030, one of 4,318 specialist construction companies in London. Its next accounts are due at Companies House on 30 April 2028, and the CT600 for the period to 31 July 2027 is due at HMRC on 31 July 2028.
Key dates
Worked out from the year end and filing history on the Companies House register.
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Financial snapshot, 2026
From the balance sheet at 31 July 2026, as filed at Companies House.
Where Constantin Mainsolution Ltd is registered
The registered office is in London (N17), in the Haringey local authority area, London. Show N17 0LX on a map.
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What happens if Constantin Mainsolution 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 April 2028.
| Companies House | Accounts delivered | Penalty |
|---|---|---|
| Up to 1 month late | 1 May 2028 to 31 May 2028 | £150 |
| 1 to 3 months late | 1 Jun 2028 to 31 Jul 2028 | £375 |
| 3 to 6 months late | 1 Aug 2028 to 31 Oct 2028 | £750 |
| More than 6 months late | From 1 Nov 2028 | £1,500 |
Penalties double if the accounts were also late the year before.
| HMRC (CT600) | From | Penalty |
|---|---|---|
| 1 day late | 1 Aug 2028 | £200 |
| 3 months late | 31 Oct 2028 | another £200 |
| 6 months late | 31 Jan 2029 | HMRC estimates the tax and adds 10% of the unpaid tax |
| 12 months late | 31 Jul 2029 | 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
- 16611030
- Status
- Active
- Company type
- Private limited company
- Incorporated
- 29 July 2025 (1 year ago)
- Registered office
- Flat 4, 12A Baronet Grove, London, N17 0LX
- Nature of business
- Other specialised construction activities n.e.c. (SIC 43999)
Landscape service activities (SIC 81300) - Year end
- 31 July (accounting reference date)
- Accounts type
- Total exemption (full)
- Last accounts made up to
- 31 July 2026
- Last confirmation statement
- 28 July 2026
Filing notes for specialist construction companies
Specialist contractors often work under CIS for main contractors. Retentions held back by the customer still count towards turnover once the work is done.
Similar companies in London
Other active specialist construction companies registered in London.
- Constral Ltd2022
- Construct and Capture Ltd2025
- Construct Data Management Ltd2023
- Construct Unite Ltd2024
- Construction Act Payment System Ltd2024
- Construction Cost Estimators Ltd2025
- Construction Engineering Solutions Ltd2022
- Construction Hollinwood Ltd2022
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Frequently asked questions
When are Constantin Mainsolution Ltd's accounts due?
Constantin Mainsolution Ltd's next accounts are due at Companies House by 30 April 2028 (in 566 days), covering the period to 31 July 2027.
When is Constantin Mainsolution Ltd's CT600 due?
The CT600 for the period to 31 July 2027 is due at HMRC by 31 July 2028, 12 months after the period end. The corporation tax itself is payable earlier, by 1 May 2028.
Is Constantin Mainsolution Ltd still trading?
Constantin Mainsolution 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 Constantin Mainsolution Ltd do?
Constantin Mainsolution Ltd is registered under Other specialised construction activities n.e.c. (SIC 43999); Landscape service activities (SIC 81300).
How old is Constantin Mainsolution Ltd?
Constantin Mainsolution Ltd was incorporated on 29 July 2025, 1 year ago.
What is the penalty if Constantin Mainsolution 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 Constantin Mainsolution 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.