- Companies
- Installers
- Mexborough
- Complex Build Ltd
Complex Build Ltd
- Company number
- 12031038
- Incorporated
- 4 Jun 20197 years trading
- Registered office
- 25 Hall Avenue, Mexborough, S64 0AH
- Nature of business
- Other construction installation; Joinery installation; Other building completion and finishing
Complex Build Ltd is a 7-year-old private limited company registered in Mexborough, company number 12031038, one of 14 installation companies (insulation, lifts, shutters and similar) in Mexborough. Its next accounts are due at Companies House on 31 March 2027, and the CT600 for the period to 30 June 2026 is due at HMRC on 30 June 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 £1,901 (+11.2%) on the year before, to £19K.
- Net assets rose in 4 of 5 year-on-year comparisons on record.
- Current assets of £18K against £6,584 owed within a year: 2.8 times cover.
- 2 employees on average during the year.
- Balance sheets on record for 6 years, 2020 to 2025.
Net assets by year
| Year end | Net assets | Cash | Current assets | Owed within a year | Employees |
|---|---|---|---|---|---|
| 30 Jun 2025 | £19K | £18K | £6,584 | 2 | |
| 30 Jun 2024 | £17K | £17K | £8,711 | 2 | |
| 30 Jun 2023 | £10K | £8,432 | £4,286 | 2 | |
| 30 Jun 2022 | £1,469 | £1,487 | £341 | 2 | |
| 30 Jun 2021 | £2 | £2 | |||
| 30 Jun 2020 | £100 | £100 |
Where Complex Build Ltd is registered
The registered office is in Mexborough (S64), in the Doncaster local authority area, Yorkshire and The Humber. Show S64 0AH on a map.
Other trade companies in S64
- SB’S Home Improvements LtdRepair services
- S J Croome Construction LtdInstallers
- Sourc LtdElectricians
- Arc Building & Interiors LtdInstallers
- 3P Project Solutions LimitedSpecialist contractors
- A&H Tyres LtdMotor traders
- Northdale Construction LtdBuilders
- A.J.W Plumbing & Heating Northern LtdPlumbers and heating engineers
Also registered at this address
2 other companies use the same registered office as Complex Build Ltd.
- Millhouses Fencing & Sheds LimitedInstallers
- Stripped Parts LimitedMachinery repair and installation
What happens if Complex Build 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 31 March 2027.
| Companies House | Accounts delivered | Penalty |
|---|---|---|
| Up to 1 month late | 1 Apr 2027 to 30 Apr 2027 | £150 |
| 1 to 3 months late | 1 May 2027 to 30 Jun 2027 | £375 |
| 3 to 6 months late | 1 Jul 2027 to 30 Sep 2027 | £750 |
| More than 6 months late | From 1 Oct 2027 | £1,500 |
Penalties double if the accounts were also late the year before.
| HMRC (CT600) | From | Penalty |
|---|---|---|
| 1 day late | 1 Jul 2027 | £200 |
| 3 months late | 30 Sep 2027 | another £200 |
| 6 months late | 30 Dec 2027 | HMRC estimates the tax and adds 10% of the unpaid tax |
| 12 months late | 30 Jun 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
- 12031038
- Status
- Active
- Company type
- Private limited company
- Incorporated
- 4 June 2019 (7 years ago)
- Registered office
- 25 Hall Avenue, Mexborough, S64 0AH
- Nature of business
- Other construction installation (SIC 43290)
Joinery installation (SIC 43320)
Other building completion and finishing (SIC 43390) - Year end
- 30 June (accounting reference date)
- Accounts type
- Micro-entity
- Last accounts made up to
- 30 June 2025
- Last confirmation statement
- 30 May 2026
Filing notes for installation companies (insulation, lifts, shutters and similar)
Installation companies (insulation, lifts, shutters, solar and similar) often buy stock and equipment up front, so stock at the year end and capital allowances both affect the tax bill.
Similar companies in Mexborough
Other active installation companies (insulation, lifts, shutters and similar) registered in Mexborough.
- Coopers Business Services Limited2008
- Forever Solar Limited2025
- Hirst Bathroom Renovations Ltd2026
- Jewitts Drywall Ltd2017
- Millhouses Fencing & Sheds Limited2017
- MSC Rope Access Solutions Ltd2024
- RGR Building Services Ltd2009
- S J Croome Construction Ltd2026
All installation companies (insulation, lifts, shutters and similar) in Mexborough · All trades in Mexborough · Installers across the UK
Frequently asked questions
When are Complex Build Ltd's accounts due?
Complex Build Ltd's next accounts are due at Companies House by 31 March 2027 (in 170 days), covering the period to 30 June 2026.
When is Complex Build Ltd's CT600 due?
The CT600 for the period to 30 June 2026 is due at HMRC by 30 June 2027, 12 months after the period end. The corporation tax itself is payable earlier, by 1 April 2027.
Is Complex Build Ltd still trading?
Complex Build 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 Complex Build Ltd do?
Complex Build Ltd is registered under Other construction installation (SIC 43290); Joinery installation (SIC 43320); Other building completion and finishing (SIC 43390).
How old is Complex Build Ltd?
Complex Build Ltd was incorporated on 4 June 2019, 7 years ago.
What is the penalty if Complex Build 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 Complex Build 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.