- Companies
- Plumbers and heating engineers
- Dover
- Proton Maintenance Ltd
Proton Maintenance Ltd
- Company number
- 16481114
- Incorporated
- 28 May 20251 year trading
- Registered office
- 196 ST. Davids Avenue, Dover, CT17 9HJ
- Nature of business
- Plumbing, heat and air-conditioning installation
Proton Maintenance Ltd is a 1-year-old private limited company registered in Dover, company number 16481114, one of 26 plumbing and heating companies in Dover. Its next accounts are due at Companies House on 29 February 2028, and the CT600 for the period to 31 May 2027 is due at HMRC on 31 May 2028.
Key dates
Worked out from the year end and filing history on the Companies House register.
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Financial snapshot, 2026
From the balance sheet at 31 May 2026, as filed at Companies House. Negative net assets mean the company owed more than it owned at that date.
Where Proton Maintenance Ltd is registered
The registered office is in Dover (CT17), in the Dover local authority area, South East. Show CT17 9HJ on a map.
Other trade companies in CT17
- LBB Solutions LimitedCivil engineering
- FCJ Contractors LtdBuilders
- K Willis Electrical Kent LimitedElectricians
- Pharesons LtdProperty developers
- Bee's Hand Car Wash LtdCleaning companies
- Baldwin Salter Property LtdProperty developers
- Aky Construction LtdSpecialist contractors
- Channel FM Cleaning & Support Services LtdCleaning companies
What happens if Proton Maintenance 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 29 February 2028.
| Companies House | Accounts delivered | Penalty |
|---|---|---|
| Up to 1 month late | 1 Mar 2028 to 31 Mar 2028 | £150 |
| 1 to 3 months late | 1 Apr 2028 to 31 May 2028 | £375 |
| 3 to 6 months late | 1 Jun 2028 to 31 Aug 2028 | £750 |
| More than 6 months late | From 1 Sep 2028 | £1,500 |
Penalties double if the accounts were also late the year before.
| HMRC (CT600) | From | Penalty |
|---|---|---|
| 1 day late | 1 Jun 2028 | £200 |
| 3 months late | 31 Aug 2028 | another £200 |
| 6 months late | 30 Nov 2028 | HMRC estimates the tax and adds 10% of the unpaid tax |
| 12 months late | 31 May 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
- 16481114
- Status
- Active
- Company type
- Private limited company
- Incorporated
- 28 May 2025 (1 year ago)
- Registered office
- 196 ST. Davids Avenue, Dover, CT17 9HJ
- Nature of business
- Plumbing, heat and air-conditioning installation (SIC 43220)
- Year end
- 31 May (accounting reference date)
- Accounts type
- Micro-entity
- Last accounts made up to
- 31 May 2026
- Last confirmation statement
- 8 June 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 Dover
Other active plumbing and heating companies registered in Dover.
- Rad Property Maintenance Ltd2023
- Relm Plumbing and Heating Ltd2011
- S.R.Heating Limited2021
- Settemp Air Conditioning Ltd2026
- Southern Plumbing Limited2004
- T J Burley Limited2010
- VFR Gas Limited2022
- Z N R Plumbing Limited2014
All plumbing and heating companies in Dover · All trades in Dover · Plumbers and heating engineers across the UK
Frequently asked questions
When are Proton Maintenance Ltd's accounts due?
Proton Maintenance Ltd's next accounts are due at Companies House by 29 February 2028 (in 504 days), covering the period to 31 May 2027.
When is Proton Maintenance Ltd's CT600 due?
The CT600 for the period to 31 May 2027 is due at HMRC by 31 May 2028, 12 months after the period end. The corporation tax itself is payable earlier, by 1 March 2028.
Is Proton Maintenance Ltd still trading?
Proton Maintenance 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 Proton Maintenance Ltd do?
Proton Maintenance Ltd is registered under Plumbing, heat and air-conditioning installation (SIC 43220).
How old is Proton Maintenance Ltd?
Proton Maintenance Ltd was incorporated on 28 May 2025, 1 year ago.
What is the penalty if Proton Maintenance 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 Proton Maintenance 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.