SDC Trailers Limited, the Toomebridge, Co. Antrim business that describes itself as the UK's leading trailer manufacturer, filed its accounts at Companies House on 10 September for the year ended 31 December 2025. Turnover rose 5.1%, from £184.6m to £194.0m. Profit fell 10.1%, from £11,827,000 to £10,632,000.
The directors name supplier prices and shipping among the causes. The staff costs note in the filed accounts also shows employer National Insurance rising more than five times faster than the wage bill. The same National Insurance change applies to every Northern Ireland business that employs people.
What the accounts show
The detail sits in the profit and loss account, filed as part of the full accounts and publicly available on SDC Trailers' Companies House record. Cost of sales rose 6.7%, from £157,591,000 to £168,136,000, faster than the 5.1% rise in turnover, which pulled gross margin down from 14.6% to 13.3%. Operating expenses rose 3.8%, from £14,583,000 to £15,142,000. Between the two, operating profit fell 13.4%, from £13,061,000 to £11,313,000, and profit for the year fell 10.1% to £10,632,000.
The directors' strategic report gives the cause: “This reduced profit is due to increased cost of sales and operating expenses (circa 7%). These increased expenses are due to cost increases from suppliers and labour cost increases due to local legislation changes.” Supplier costs and shipping get the first mention. Labour costs get the second — and the employee information note two pages later gives the figures.
Employer National Insurance against wages
SDC Trailers employed an average of 629 people in 2025, up from 594 in 2024 — a 5.9% rise, almost all of it in production roles (573, up from 536). Wages and salaries rose 3.96%, from £21,435,000 to £22,284,000, roughly in line with that extra headcount. Social security costs — employer National Insurance — rose 20.81%, from £2,201,000 to £2,659,000. Divide each year's NI bill by that year's average headcount and the cost per employee rose from £3,705 to £4,227 — a 14.1% increase per head, on top of the extra heads.
| SDC Trailers Limited — staff costs | 2024 | 2025 | Change |
|---|---|---|---|
| Average headcount | 594 | 629 | +5.9% |
| Wages and salaries | £21,435,000 | £22,284,000 | +4.0% |
| Social security costs (employer NI) | £2,201,000 | £2,659,000 | +20.8% |
| Other pension costs | £1,111,000 | £1,244,000 | +12.0% |
| Total staff costs | £24,747,000 | £26,187,000 | +5.8% |
That pattern is what the UK-wide change to employer National Insurance, effective from 6 April 2025, does to a payroll. The rate rose from 13.8% to 15%, and the secondary threshold — the pay level above which an employer starts paying NI on that employee — fell from £9,100 to £5,000. SDC Trailers' 2025 financial year runs across the old rules for the first quarter and the new rules for the remaining three, which is consistent with a rise well above wage growth but below what a full year entirely under the new rules would have produced. Employment Allowance, which offsets the first slice of an eligible employer's annual bill, rose in the same change from £5,000 to £10,500 — but that exemption cuts out once a company's prior-year employer NI liability passes £100,000, which rules SDC Trailers out of it entirely at this scale.
What the same shift costs a smaller Northern Ireland business
Here is the same change on an illustrative 40-person Co. Antrim manufacturer paying an average salary of £30,000 — small enough to still qualify for Employment Allowance, which SDC Trailers no longer does.
| Illustrative 40-person Co. Antrim manufacturer, £30,000 average salary | 2024/25 rules | 2025/26 & 2026/27 rules |
|---|---|---|
| Employer NI rate | 13.8% above £9,100 | 15% above £5,000 |
| Employer NI before allowance (40 staff) | £115,368 | £150,000 |
| Employment Allowance | −£5,000 | −£10,500 |
| Net employer NI | £110,368 | £139,500 |
Wage bill unchanged at £1.2m. Employer NI up £29,132 — a 26.4% rise — with no new hires and no pay rises. SDC Trailers' accounts show the same pattern at a larger scale: a wage bill that moved a few percent, and an NI bill that moved by a multiple of it, because the rate and the threshold both moved against every pound of pay above £5,000.
GB and NI trading in the same filing
One line in SDC Trailers' strategic report concerns trade rather than National Insurance. Among the ways the company manages labour supply risk, the directors note there is “a dedicated Duty team to handle all GB/NI trading.” A Northern Ireland manufacturer moving its own goods to its own GB customers still needs a team whose job is customs and duty paperwork on that internal movement — a cost and a process most GB-only manufacturers do not carry. Windsor Framework paperwork applies to goods an NI business moves into Great Britain, as well as to trade across the border with the Republic.
What to do this week
Split your own wage growth from your own NI growth for the last two years, the way this note does for SDC Trailers, instead of reading a single "staff costs" total. If the NI line moved faster than the wage line, the difference comes from the policy change, so build it into next year's payroll budget. Our payroll team can pull that split from your own figures in an afternoon.
If you move goods between Northern Ireland and Great Britain, even within your own business, confirm your duty and customs paperwork covers it. Our cross-border VAT guide sets out the rules, and our management accounts service reports this kind of cost every month.
What is still uncertain, and when we'll know
SDC Trailers' accounts don't break the roughly 7% rise in cost of sales and operating expenses down between supplier costs, shipping and labour specifically — the directors' report bundles all three into one sentence, so the exact split beyond what's shown in the staff costs note is an estimate bounded by the figures actually filed. There's also no announced change to the employer NI rate or the £5,000 secondary threshold for 2026/27 — both are confirmed unchanged from 2025/26 — but a future Budget could move either again, and the next one hasn't been dated yet. In the meantime, check whether your own NI line is still growing faster than your wage line, and by how much.
