- Companies
- Glaziers
- Porthmadog
- White Diamond Windows Ltd
White Diamond Windows Ltd
- Company number
- 17128302
- Incorporated
- 31 Mar 2026
- Registered office
- ST. Davids Building, Lombard Street, Porthmadog, LL49 9AP
- Nature of business
- Glazing
White Diamond Windows Ltd is a newly incorporated private limited company registered in Porthmadog, company number 17128302, one of the UK's glazing companies. Its next accounts are due at Companies House on 31 December 2027, and its first CT600 is due at HMRC on 30 March 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 White Diamond Windows Ltd is registered
The registered office is in Porthmadog (LL49), in the Gwynedd local authority area, Wales. Show LL49 9AP on a map.
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Also registered at this address
13 other companies use the same registered office as White Diamond Windows Ltd.
- B & S Siting LimitedInstallers
- Bricsan CyfProperty developers
- Carwyn Ap Plymio A Gwresogi CyfPlumbers and heating engineers
- D.Thomas Electrical CyfElectricians
- E H A'i Fab Ynni Adnewyddadol & Trydanol CyfElectricians
- E.Jones Williams and Son LimitedProperty developers
- Elis Llywelyn Williams CyfPlumbers and heating engineers
- Ffenestri Dwyfor Windows CyfGlaziers
- G Jones Contracts LimitedSpecialist contractors
- N Commercial LtdMotor traders
- North West Wales Electrical LtdElectricians
- R J Jones Plumbing & Heating LtdPlumbers and heating engineers
- TK Resin Driveways LtdSpecialist contractors
What happens if White Diamond Windows 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 December 2027.
| Companies House | Accounts delivered | Penalty |
|---|---|---|
| Up to 1 month late | 1 Jan 2028 to 31 Jan 2028 | £150 |
| 1 to 3 months late | 1 Feb 2028 to 31 Mar 2028 | £375 |
| 3 to 6 months late | 1 Apr 2028 to 30 Jun 2028 | £750 |
| More than 6 months late | From 1 Jul 2028 | £1,500 |
Penalties double if the accounts were also late the year before.
| HMRC (CT600) | From | Penalty |
|---|---|---|
| 1 day late | 1 Apr 2028 | £200 |
| 3 months late | 30 Jun 2028 | another £200 |
| 6 months late | 30 Sep 2028 | HMRC estimates the tax and adds 10% of the unpaid tax |
| 12 months late | 31 Mar 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
- 17128302
- Status
- Active
- Company type
- Private limited company
- Incorporated
- 31 March 2026
- Registered office
- ST. Davids Building, Lombard Street, Porthmadog, LL49 9AP
- Nature of business
- Glazing (SIC 43342)
- Year end
- 31 March (accounting reference date)
- Accounts type
- No accounts filed yet
Filing notes for glazing companies
Glazing companies often take deposits before work starts. Deposits held at the year end are a liability, not income, until the job is done.
Similar companies in Porthmadog
Other active glazing companies registered in Porthmadog.
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Frequently asked questions
When are White Diamond Windows Ltd's accounts due?
White Diamond Windows Ltd's next accounts are due at Companies House by 31 December 2027 (in 444 days), covering the period to 31 March 2027.
When is White Diamond Windows 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 30 March 2027, due by 30 March 2028, and one for the period to 31 March 2027, due by 31 March 2028. Corporation tax is payable 9 months and 1 day after the end of each.
Is White Diamond Windows Ltd still trading?
White Diamond Windows 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 White Diamond Windows Ltd do?
White Diamond Windows Ltd is registered under Glazing (SIC 43342).
How old is White Diamond Windows Ltd?
White Diamond Windows Ltd was incorporated on 31 March 2026, less than a year ago.
What is the penalty if White Diamond Windows 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 White Diamond Windows 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.