[ Corporation Tax Specialists ]
Corporation Tax Accountant London
As your corporation tax accountant in London, we file your CT600 accurately and on time — and plan ahead to keep your effective rate as low as legitimately possible. From marginal relief to capital allowances on plant and machinery, we know where construction companies save.
CT600
Filed accurately, every deadline
Marginal relief
Optimised between £50k–£250k
Allowances
Capital allowances maximised
Planning
Year-round, not just filing
Corporation tax is the biggest single tax most construction companies pay. The main rate is 25% on profits over £250,000, with marginal relief tapering the rate down to 19% for profits between £50,000 and £250,000. Getting the calculation right — especially at the margins where marginal relief applies — can save thousands of pounds that a careless filing would miss.
For construction companies, the biggest savings usually come from capital allowances. Plant, machinery, vans, tools, scaffolding and equipment all qualify for allowances that reduce your taxable profit. We make sure every qualifying asset is claimed, including the annual investment allowance (AIA) which lets you deduct the full cost of most plant in the year of purchase, up to £1 million per year.
We also look at loss relief — carrying losses back to reclaim tax already paid, or carrying them forward to offset future profits. And for construction companies investing in new technology or innovative methods, we assess whether R&D tax credits apply. The point is not just to file your CT600 on time — it is to make sure you are paying the lowest legitimate amount of tax.
[ What We Handle ]
Corporation Tax Accountant London — the full scope.
- ◢CT600 corporation tax return preparation and filing
- ◢Marginal relief calculations for mid-band profits
- ◢Capital allowances on plant, machinery and vehicles
- ◢Research and development (R&D) relief for construction tech
- ◢Loss relief and carry-back / carry-forward planning
- ◢Quarterly corporation tax payments on account
[ Frequently Asked Questions ]
Corporation Tax Accountant London — your questions answered.
What is the corporation tax rate for construction companies?
The main corporation tax rate is 25% on profits over £250,000. Companies with profits between £50,000 and £250,000 benefit from marginal relief, which tapers the effective rate down to 19% at the £50,000 small profits threshold. We calculate marginal relief precisely so you pay the correct — and lowest — amount.
When is the CT600 deadline?
Your CT600 corporation tax return must be filed 12 months after your company's accounting period end. Corporation tax itself must be paid 9 months and 1 day after the accounting period end. Larger companies may also need to make quarterly payments on account. We track all of these deadlines for you.
What capital allowances can construction companies claim?
Construction companies can claim capital allowances on plant, machinery, vans, tools, scaffolding, equipment, and certain building fixtures. The Annual Investment Allowance (AIA) lets you deduct the full cost of most qualifying plant up to £1 million per year. We review every asset purchase to make sure nothing is missed.
Can construction companies claim R&D tax credits?
Yes, if you are investing in developing new or improved construction methods, materials, or technology. R&D tax credits can provide a significant tax saving or even a cash refund for loss-making companies. We assess whether your activities qualify and handle the claim with HMRC.
What happens if I miss my corporation tax deadline?
HMRC issues automatic penalties for late CT600 filing: £100 immediately, then £100 after three months, plus 10% of the estimated tax after six months and another 10% after 12 months. Interest is also charged on late tax payments. We make sure your return is filed well before the deadline.
Ready to talk to a specialist?
Book a free financial site review and we'll review your CIS, tax and accounts — no obligation.