- Companies
- Electricians
- Hull
- Carbon Synergy Limited
Carbon Synergy Limited
- Company number
- 06504230
- Incorporated
- 14 Feb 200818 years trading
- Registered office
- Holderness House Tower House Lane, Saltend, Hull, East Yorkshire, HU12 8EE
- Nature of business
- Electrical installation
Carbon Synergy Limited is a 18-year-old private limited company registered in Hull, company number 06504230, one of 207 electrical contractors in Hull. Its next accounts are due at Companies House on 31 December 2026, and the CT600 for the period to 31 March 2026 is due at HMRC on 31 March 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 £159K (+15.5%) on the year before, to £1.2M.
- Net assets rose in 7 of 9 year-on-year comparisons on record.
- Current assets of £2.5M against £1.4M owed within a year: 1.8 times cover.
- 35 employees on average, down from 36 the year before.
- Balance sheets on record for 10 years, 2016 to 2025.
Net assets by year
| Year end | Net assets | Cash | Current assets | Owed within a year | Employees |
|---|---|---|---|---|---|
| 31 Mar 2025 | £1.2M | £1.4M | £2.5M | £1.4M | 35 |
| 31 Mar 2024 | £1M | £799K | £1.6M | £760K | 36 |
| 31 Mar 2023 | £1.2M | £968K | £1.4M | £675K | 36 |
| 31 Mar 2022 | £1.1M | £1.2M | £1.5M | £831K | 29 |
| 31 Mar 2021 | £825K | £628K | £988K | £241K | 32 |
| 31 Mar 2020 | £590K | £400K | £788K | £469K | 27 |
| 31 Mar 2019 | £407K | £594K | £935K | £750K | 21 |
| 31 Mar 2018 | £335K | £162K | £518K | £443K | |
| 31 Mar 2017 | £399K | £123K | £412K | £574K | |
| 31 Mar 2016 | £393K | £422K | £774K | £221K |
Where Carbon Synergy Limited is registered
The registered office is in Hull (HU12), in the East Riding of Yorkshire local authority area, Yorkshire and The Humber. Show HU12 8EE on a map.
Other trade companies in HU12
- SM Electrical Group LtdMachinery repair and installation
- Aek Contracts LimitedPainters and decorators
- Amhil Automotive LtdMechanics and garages
- Jack Robinson (Hull) LtdMachinery repair and installation
- Liftx Group LimitedMachinery repair and installation
- Kingfisher Gas & Plumbing LtdPlumbers and heating engineers
- STB Energy LtdMachinery repair and installation
- Frame-Tech UPVC Windows & Doors LtdFinishing trades
Also registered at this address
1 other company uses the same registered office as Carbon Synergy Limited.
- Carbon Climate LimitedPlumbers and heating engineers
What happens if Carbon Synergy Limited 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 December 2026.
| Companies House | Accounts delivered | Penalty |
|---|---|---|
| Up to 1 month late | 1 Jan 2027 to 31 Jan 2027 | £150 |
| 1 to 3 months late | 1 Feb 2027 to 31 Mar 2027 | £375 |
| 3 to 6 months late | 1 Apr 2027 to 30 Jun 2027 | £750 |
| More than 6 months late | From 1 Jul 2027 | £1,500 |
Penalties double if the accounts were also late the year before.
| HMRC (CT600) | From | Penalty |
|---|---|---|
| 1 day late | 1 Apr 2027 | £200 |
| 3 months late | 30 Jun 2027 | another £200 |
| 6 months late | 30 Sep 2027 | HMRC estimates the tax and adds 10% of the unpaid tax |
| 12 months late | 31 Mar 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
- 06504230
- Status
- Active
- Company type
- Private limited company
- Incorporated
- 14 February 2008 (18 years ago)
- Registered office
- Holderness House Tower House Lane, Saltend, Hull, East Yorkshire, HU12 8EE
- Nature of business
- Electrical installation (SIC 43210)
- Year end
- 31 March (accounting reference date)
- Accounts type
- Total exemption (full)
- Last accounts made up to
- 31 March 2025
- Last confirmation statement
- 25 June 2026
- Charges (mortgages)
- 1 outstanding of 2 registered
- Previous names
- Carbon Electric Limited (until 3 Jan 2024)
M Hutton Electrical Services Limited (until 9 Jun 2010)
Filing notes for electrical contractors
Electrical contracting companies are often a director plus a van and tools. Most fall within the micro-entity rules, so the accounts filed at Companies House are short, and the CT600 carries the tax detail.
Similar companies in Hull
Other active electrical contractors registered in Hull.
- Cater-Care Commercial Kitchen Services Ltd2025
- CD Services Electrical Ltd2006
- Celect Electrical (UK) Ltd2010
- Centurion Electro-Mechanical Solutions Ltd2020
- City Alarms & Security Ltd2022
- CLM Electrical (East Yorkshire) Limited2024
- CM Electrical (Hull) Limited2025
- Cma-UK Ltd2026
All electrical contractors in Hull · All trades in Hull · Electricians across the UK
Frequently asked questions
When are Carbon Synergy Limited's accounts due?
Carbon Synergy Limited's next accounts are due at Companies House by 31 December 2026 (in 79 days), covering the period to 31 March 2026.
When is Carbon Synergy Limited's CT600 due?
The CT600 for the period to 31 March 2026 is due at HMRC by 31 March 2027, 12 months after the period end. The corporation tax itself is payable earlier, by 1 January 2027.
Is Carbon Synergy Limited still trading?
Carbon Synergy Limited 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 Carbon Synergy Limited do?
Carbon Synergy Limited is registered under Electrical installation (SIC 43210).
How old is Carbon Synergy Limited?
Carbon Synergy Limited was incorporated on 14 February 2008, 18 years ago.
What is the penalty if Carbon Synergy Limited 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 Carbon Synergy Limited 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.