- Companies
- Electricians
- Castlewellan
- S.D.E Electrical Systems Ltd
S.D.E Electrical Systems Ltd
- Company number
- NI739637
- Incorporated
- 10 Apr 2026
- Registered office
- 16 Upper Square, Castlewellan, BT31 9DD
- Nature of business
- Electrical installation
S.D.E Electrical Systems Ltd is a newly incorporated private limited company registered in Castlewellan, company number NI739637, one of 10 electrical contractors in Castlewellan. Its next accounts are due at Companies House on 10 January 2028, and its first CT600 is due at HMRC on 9 April 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 S.D.E Electrical Systems Ltd is registered
The registered office is in Castlewellan (BT31), in the Newry, Mourne and Down local authority area, Northern Ireland. Show BT31 9DD on a map.
Other trade companies in BT31
- Ogm26 LtdGroundworks and demolition
- Treadline Tyre & Auto Services LtdMechanics and garages
- CB Fire Compliance LimitedSpecialist contractors
- Cea Joinery LtdJoiners and carpenters
- NI.CBR LtdMechanics and garages
- Jam Civils & Utilities LtdGroundworks and demolition
- B McVeigh Mechanical LtdPlumbers and heating engineers
- Dundrinne Developments LimitedProperty developers
Also registered at this address
18 other companies use the same registered office as S.D.E Electrical Systems Ltd.
- Agd Plumbing & Heating LtdPlumbers and heating engineers
- B R Building & Joinery LimitedFinishing trades
- Cea Joinery LtdJoiners and carpenters
- Cisco Plumbing & Heating LtdPlumbers and heating engineers
- Clonkeel Joinery LtdProperty developers
- CMC Surfacing & Groundwork LtdBuilders
- Construction Sealants (Ireland) LtdSpecialist contractors
- Echo Direct Construction LtdBuilders
- Jam Civils & Utilities LtdGroundworks and demolition
- Kelly New Homes LimitedBuilders
- KP Civil LtdGroundworks and demolition
- Mark Gallagher Building LtdBuilders
- Matthews Electrical Services (N.I.) LimitedElectricians
- MJD Building LtdBuilders
- Morgan Plumbing Services LtdPlumbers and heating engineers
- PDM Plumbing Services LtdPlumbers and heating engineers
- RW Carpentry & Construction LtdJoiners and carpenters
- Seac Electrical LtdElectricians
What happens if S.D.E Electrical Systems 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 10 January 2028.
| Companies House | Accounts delivered | Penalty |
|---|---|---|
| Up to 1 month late | 11 Jan 2028 to 10 Feb 2028 | £150 |
| 1 to 3 months late | 11 Feb 2028 to 10 Apr 2028 | £375 |
| 3 to 6 months late | 11 Apr 2028 to 10 Jul 2028 | £750 |
| More than 6 months late | From 11 Jul 2028 | £1,500 |
Penalties double if the accounts were also late the year before.
| HMRC (CT600) | From | Penalty |
|---|---|---|
| 1 day late | 1 May 2028 | £200 |
| 3 months late | 30 Jul 2028 | another £200 |
| 6 months late | 30 Oct 2028 | HMRC estimates the tax and adds 10% of the unpaid tax |
| 12 months late | 30 Apr 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
- NI739637
- Status
- Active
- Company type
- Private limited company
- Incorporated
- 10 April 2026
- Registered office
- 16 Upper Square, Castlewellan, BT31 9DD
- Nature of business
- Electrical installation (SIC 43210)
- Year end
- 30 April (accounting reference date)
- Accounts type
- No accounts filed yet
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 Castlewellan
Other active electrical contractors registered in Castlewellan.
- S.K.M. Electrical Ltd2006
- Seac Electrical Ltd2018
- Epic Electrical Services Limited2020
- JC Electrics (NI) Limited2012
- JMC Connect Ltd2022
- JMC Electrics Holdings Ltd2026
- Matthews Electrical Services (N.I.) Limited2016
- RPG Electrics Ltd2024
All electrical contractors in Castlewellan · All trades in Castlewellan · Electricians across the UK
Frequently asked questions
When are S.D.E Electrical Systems Ltd's accounts due?
S.D.E Electrical Systems Ltd's next accounts are due at Companies House by 10 January 2028 (in 455 days), covering the period to 30 April 2027.
When is S.D.E Electrical Systems 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 9 April 2027, due by 9 April 2028, and one for the period to 30 April 2027, due by 30 April 2028. Corporation tax is payable 9 months and 1 day after the end of each.
Is S.D.E Electrical Systems Ltd still trading?
S.D.E Electrical Systems 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 S.D.E Electrical Systems Ltd do?
S.D.E Electrical Systems Ltd is registered under Electrical installation (SIC 43210).
How old is S.D.E Electrical Systems Ltd?
S.D.E Electrical Systems Ltd was incorporated on 10 April 2026, less than a year ago.
What is the penalty if S.D.E Electrical Systems 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 S.D.E Electrical Systems 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.