Corporation Tax Accountants London
Corporation Tax returns, CT600 preparation, taxable profit calculations and practical tax support for UK limited companies.
We connect your company’s bookkeeping and year-end accounts with the tax computation, identify issues early and agree the work required before filing.
Corporation Tax Is More Than Completing a CT600
Your Company Tax Return starts with accurate accounts, but accounting profit and taxable profit are not always the same.
Adjustments may be needed for non-deductible expenses, capital allowances, losses, related-party transactions and director balances. ATA reviews the underlying records and prepares Corporation Tax computations and returns as part of an agreed engagement.
We support owner-managed limited companies, consultants, property businesses, contractors, retailers and other trading companies across London and the UK through digital accounting processes.
Corporation Tax & CT600 Services
CT600 Preparation & Filing
Prepare a Company Tax Return, supporting computations and required schedules using the company’s accounting and tax information.
Accounts-to-Tax Reconciliation
Review accounting profit, adjustments and supporting records before calculating profits chargeable to Corporation Tax.
Accounting & bookkeeping →Expenses & Allowances
Consider business expenditure, depreciation adjustments, qualifying capital expenditure and potentially available allowances.
Marginal Relief & Associated Companies
Review applicable rates and whether associated-company rules or shorter periods change the relevant profit thresholds.
Director’s Loan Accounts
Identify overdrawn balances, relevant section 455 issues, loan benefits and possible CT600A reporting requirements.
Company and director tax guidance →Tax Planning & HMRC Correspondence
Review company tax matters ahead of deadlines and assist with appropriate HMRC enquiries and correspondence within the agreed scope.
What Corporation Tax Rate Does Your Company Pay?
The rate depends on the company’s taxable profits and applicable rules, rather than simply its turnover.
Generally for profits of £50,000 or less, subject to eligibility and adjusted thresholds.
Eligible companies between the adjusted thresholds may receive marginal relief rather than pay a flat rate.
Generally applies above £250,000 in profits, subject to adjusted limits and special regimes.
The standard £50,000 and £250,000 limits may be divided between associated companies and proportionately reduced for short accounting periods. Special rules apply to some types of income and companies. Check the relevant financial year and facts before relying on any rate.
HMRC: Corporation Tax rates and reliefs ↗Corporation Tax Payment and Filing Dates Are Different
Usually 9 Months + 1 Day
For companies outside the instalment-payment regime, Corporation Tax is normally due nine months and one day after the end of the tax accounting period.
Usually Within 12 Months
A Company Tax Return is normally due within 12 months of the end of the accounting period it covers, where HMRC requires a return.
Example: for a standard accounting period ending 31 March 2026, the usual Corporation Tax payment date is 1 January 2027 and the CT600 filing date is 31 March 2027. Companies subject to instalment payments have different payment rules.
HMRC: Company Tax Return rules ↗Company Tax Matters Worth Reviewing Before Filing
Directors Taking Money Out
Salary, dividends, expense reimbursements and loans are not interchangeable. Poorly documented withdrawals can create both accounting and tax problems.
Capital Allowances
Purchases recorded as fixed assets may qualify for allowances, subject to the nature of the asset, dates, limits and other conditions.
Loss-Making Companies
Trading losses, carried-forward relief and group arrangements require a review of the applicable conditions and restrictions.
Associated Companies
Companies under common control can affect marginal relief limits and other thresholds even where each company maintains separate accounts.
Understand. Reconcile. Prepare. File.
- 01 — Review the Scope
Confirm business activity, accounting period, record quality, filing history and relevant complexities.
- 02 — Prepare the Computation
Connect year-end accounts to tax adjustments, allowances, reliefs and relevant supporting schedules.
- 03 — Obtain Approval & Submit
Provide the proposed figures for review and approval before authorised filing, and highlight payment obligations.
Corporation Tax Support for Different Companies
Owner-Managed Companies
CT600 preparation, director remuneration, loan account reviews and year-end tax calculations.
Consultants & Professional Services
Support with taxable business profits, expenses, contractors and connected personal tax matters.
Construction & Specialist Trades
Company tax support linked to CIS records, payroll, contract costs and bookkeeping.
Property & Investment Companies
Review rental company profits, financing entries and tax matters appropriate to investment businesses.
Property accounting services →Explore Related Accounting & Tax Support
These services connect the company tax return with the financial records and wider tax matters that sit behind it.
For detailed treatment of director withdrawals, section 455 and CT600A, see the Director’s Loan and Company Tax guides linked from our Tax Services pillar.
Corporation Tax Resources
HMRC — Corporation Tax Rates
Current standard rates, profit thresholds and marginal relief guidance.
Read official guidance ↗HMRC — Company Tax Returns
Who must file, return requirements, deadlines and penalties.
Read official guidance ↗HMRC — Paying Corporation Tax
Payment deadlines, references and instalment payment considerations.
Read official guidance ↗Companies House
Statutory accounts and filing obligations separate from Corporation Tax returns.
Read official guidance ↗Corporation Tax Accountants — Frequently Asked Questions
Does my company need a CT600 if it made a loss?
If HMRC has issued a notice to deliver a Company Tax Return, the company generally needs to file even if it made a loss or has no Corporation Tax to pay.
Is Corporation Tax calculated on turnover?
No. It is generally charged on taxable profits and certain gains after relevant adjustments, deductions and reliefs, not directly on gross sales.
Are year-end accounts and a CT600 the same filing?
No. Statutory company accounts and Company Tax Returns have different legal purposes and deadlines. Related financial information may be used in both.
When must Corporation Tax be paid?
For companies not paying by instalments, normally nine months and one day after the accounting period ends. The tax return itself is normally due later, within twelve months.
Can ATA help with section 455 and director’s loans?
Yes, relevant director’s loan account issues can be included in a scoped Corporation Tax review, including consideration of section 455 and CT600A reporting.
Can a company claim relief for business expenses?
Many qualifying business expenses are deductible, but tax rules differ from accounting treatment. Some costs are disallowed or require specific relief such as capital allowances.
Can ATA take over from our current accountant?
Subject to engagement acceptance, appropriate checks and professional clearance, we can agree a transition plan and identify the information needed.
How much do Corporation Tax accountants charge?
Fees depend on bookkeeping quality, company complexity, transactions, adjustments, related companies and associated annual accounts requirements. ATA reviews the scope before quoting.
Need Help With a Corporation Tax Return?
Tell us your company year-end, bookkeeping position, filing requirements and any outstanding tax issues. We’ll assess the work required and provide a scope and quotation where we can assist.
Accounting & Tax Associates Ltd · London-wide digital accounting services · info@ataxa.co.uk