- Company number
- 17375902
- Incorporated
- 3 Aug 2026
- Registered office
- Office 1735 60 Tottenham Court Road, Fitzrovia, London, W1T 2EW
- Nature of business
- Construction of domestic buildings; Other building completion and finishing; Agents involved in the sale of timber and building materials; Other business support service activities n.e.c.
Mastrix Ltd is a newly incorporated private limited company registered in London, company number 17375902, one of 12,075 building contractors in London. Its next accounts are due at Companies House on 3 May 2028, and its first CT600 is due at HMRC on 2 August 2028.
Key dates
This company has not filed accounts yet. First accounts are due 21 months after incorporation, and the first period can run longer than a year.
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Where Mastrix Ltd is registered
The registered office is in London (W1T), in the Camden local authority area, London. Show W1T 2EW on a map.
Other trade companies in W1T
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- 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
What happens if Mastrix 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 3 May 2028.
| Companies House | Accounts delivered | Penalty |
|---|---|---|
| Up to 1 month late | 4 May 2028 to 3 Jun 2028 | £150 |
| 1 to 3 months late | 4 Jun 2028 to 3 Aug 2028 | £375 |
| 3 to 6 months late | 4 Aug 2028 to 3 Nov 2028 | £750 |
| More than 6 months late | From 4 Nov 2028 | £1,500 |
Penalties double if the accounts were also late the year before.
| HMRC (CT600) | From | Penalty |
|---|---|---|
| 1 day late | 1 Sep 2028 | £200 |
| 3 months late | 30 Nov 2028 | another £200 |
| 6 months late | 28 Feb 2029 | HMRC estimates the tax and adds 10% of the unpaid tax |
| 12 months late | 31 Aug 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
- 17375902
- Status
- Active
- Company type
- Private limited company
- Incorporated
- 3 August 2026
- Registered office
- Office 1735 60 Tottenham Court Road, Fitzrovia, London, W1T 2EW
- Nature of business
- Construction of domestic buildings (SIC 41202)
Other building completion and finishing (SIC 43390)
Agents involved in the sale of timber and building materials (SIC 46130)
Other business support service activities n.e.c. (SIC 82990) - Year end
- 31 August (accounting reference date)
- Accounts type
- No accounts filed yet
Filing notes for building contractors
Building companies often run the Construction Industry Scheme as a contractor, a subcontractor or both. CIS deductions suffered during the year are set against the PAYE bill, and any unrecovered balance at the year end matters when the accounts are drawn up.
Similar companies in London
Other active building contractors registered in London.
- Mat Constructions London Ltd2020
- Mat-Building Services Ltd2025
- Mata Building Ltd2018
- Mate Moving Company Ltd2023
- Matei Construction Ltd2020
- Matei Construction Management Limited2025
- Matena Ltd2016
- Mateo Construction Ltd2023
All building contractors in London · All trades in London · Builders across the UK
Frequently asked questions
When are Mastrix Ltd's accounts due?
Mastrix Ltd's next accounts are due at Companies House by 3 May 2028 (in 569 days), covering the period to 31 August 2027.
When is Mastrix Ltd's CT600 due?
The first accounts cover more than 12 months, so there are two Company Tax Returns: one for the 12 months to 2 August 2027, due by 2 August 2028, and one for the period to 31 August 2027, due by 31 August 2028. Corporation tax is payable 9 months and 1 day after the end of each.
Is Mastrix Ltd still trading?
Mastrix 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 Mastrix Ltd do?
Mastrix Ltd is registered under Construction of domestic buildings (SIC 41202); Other building completion and finishing (SIC 43390); Agents involved in the sale of timber and building materials (SIC 46130); Other business support service activities n.e.c. (SIC 82990).
How old is Mastrix Ltd?
Mastrix Ltd was incorporated on 3 August 2026, less than a year ago.
What is the penalty if Mastrix 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 Mastrix 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.