- Companies
- Plumbers and heating engineers
- Portsmouth
- South Downs Mechanical Limited
South Downs Mechanical Limited
- Company number
- 11318417
- Incorporated
- 19 Apr 20188 years trading
- Registered office
- 23 Portsmouth Enterprise Centre, Quartremaine Road, Portsmouth, PO3 5QT
- Nature of business
- Plumbing, heat and air-conditioning installation
South Downs Mechanical Limited is a 8-year-old private limited company registered in Portsmouth, company number 11318417, one of 141 plumbing and heating companies in Portsmouth. Its next accounts are due at Companies House on 31 January 2027, and the CT600 for the period to 30 April 2026 is due at HMRC on 30 April 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 down £42 (-3.9%) on the year before, to £1,042.
- Net assets rose in 3 of 6 year-on-year comparisons on record.
- Current assets of £76K against £90K owed within a year: 0.8 times cover.
- 3 employees on average during the year.
- Balance sheets on record for 7 years, 2019 to 2025.
Net assets by year
| Year end | Net assets | Cash | Current assets | Owed within a year | Employees |
|---|---|---|---|---|---|
| 30 Apr 2025 | £1,042 | £5,199 | £76K | £90K | 3 |
| 30 Apr 2024 | £1,084 | £50K | £87K | £98K | 3 |
| 30 Apr 2023 | £1,050 | £4,844 | £40K | £48K | 3 |
| 30 Apr 2022 | £13K | £21K | £54K | £48K | 2 |
| 30 Apr 2021 | £20K | £6,013 | £42K | £27K | 1 |
| 30 Apr 2020 | £9,409 | £12K | £19K | £14K | 0 |
| 30 Apr 2019 | £1 | £1 |
Where South Downs Mechanical Limited is registered
The registered office is in Portsmouth (PO3), in the Portsmouth local authority area, South East. Show PO3 5QT on a map.
Other trade companies in PO3
- GJM Construction LtdBuilders
- Al Fajar Building LimitedFinishing trades
- New Milton Decor LtdPainters and decorators
- Portsmouth Autos LtdMechanics and garages
- Henley Roofing Group LimitedInstallers
- I’M Covered 365 Ac LtdPlumbers and heating engineers
- Scope Bodyshop LtdMechanics and garages
- GP Technical LtdSpecialist contractors
What happens if South Downs Mechanical 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 January 2027.
| Companies House | Accounts delivered | Penalty |
|---|---|---|
| Up to 1 month late | 1 Feb 2027 to 28 Feb 2027 | £150 |
| 1 to 3 months late | 1 Mar 2027 to 30 Apr 2027 | £375 |
| 3 to 6 months late | 1 May 2027 to 31 Jul 2027 | £750 |
| More than 6 months late | From 1 Aug 2027 | £1,500 |
Penalties double if the accounts were also late the year before.
| HMRC (CT600) | From | Penalty |
|---|---|---|
| 1 day late | 1 May 2027 | £200 |
| 3 months late | 30 Jul 2027 | another £200 |
| 6 months late | 30 Oct 2027 | HMRC estimates the tax and adds 10% of the unpaid tax |
| 12 months late | 30 Apr 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
- 11318417
- Status
- Active
- Company type
- Private limited company
- Incorporated
- 19 April 2018 (8 years ago)
- Registered office
- 23 Portsmouth Enterprise Centre, Quartremaine Road, Portsmouth, PO3 5QT
- Nature of business
- Plumbing, heat and air-conditioning installation (SIC 43220)
- Year end
- 30 April (accounting reference date)
- Accounts type
- Total exemption (full)
- Last accounts made up to
- 30 April 2025
- Last confirmation statement
- 18 April 2026
Filing notes for plumbing and heating companies
Plumbing and heating companies frequently work under CIS for main contractors and also directly for homeowners, so turnover can mix CIS and non-CIS income.
Similar companies in Portsmouth
Other active plumbing and heating companies registered in Portsmouth.
- Spiwell Mechanical Services Ltd2023
- Square Gas Limited2023
- SRS Property Maintenance Ltd2026
- Stellar Gas Services Ltd2019
- Sylvadale Limited2012
- Theo Enterprises Limited2021
- Thermaflow Heating & Plumbing Solutions Limited2021
- Thirty Something Collective Ltd2024
All plumbing and heating companies in Portsmouth · All trades in Portsmouth · Plumbers and heating engineers across the UK
Frequently asked questions
When are South Downs Mechanical Limited's accounts due?
South Downs Mechanical Limited's next accounts are due at Companies House by 31 January 2027 (in 110 days), covering the period to 30 April 2026.
When is South Downs Mechanical Limited's CT600 due?
The CT600 for the period to 30 April 2026 is due at HMRC by 30 April 2027, 12 months after the period end. The corporation tax itself is payable earlier, by 1 February 2027.
Is South Downs Mechanical Limited still trading?
South Downs Mechanical 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 South Downs Mechanical Limited do?
South Downs Mechanical Limited is registered under Plumbing, heat and air-conditioning installation (SIC 43220).
How old is South Downs Mechanical Limited?
South Downs Mechanical Limited was incorporated on 19 April 2018, 8 years ago.
What is the penalty if South Downs Mechanical 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 South Downs Mechanical 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.