The CT1 Return is the mandatory annual corporation tax return that Irish companies file with Revenue Commissioners. It includes computations of taxable profits, tax liabilities, and supporting schedules, due nine months after the financial year end. Late filing incurs penalties and interest, making timely preparation essential for compliance.
The CT1 Return is the primary form used by Irish companies to report their corporation tax position to the Revenue Commissioners each year. This mandatory filing summarises your company's taxable profits, allowable deductions, and the resulting tax liability for the accounting period, serving as the cornerstone of corporate tax compliance in Ireland.
When you file a CT1 Return, you provide detailed computations that reconcile your company's financial statements with tax law. This includes adjustments for items like capital allowances, tax relief claims, and non-deductible expenses. Revenue uses this information to assess whether your company has correctly calculated and paid its 12.5% corporation tax on trading profits.
For founders, the CT1 Return represents the culmination of your annual tax cycle. Preparing it requires close collaboration with your accountant, who ensures accuracy to avoid audits or adjustments. Filing on time preserves your good standing and prevents additional costs from penalties or tax interest.
Your CT1 Return must be filed within nine months of your financial year end, regardless of whether your company made a profit or loss. Corporation tax payment follows shortly after, due nine months and one day after the year end for most businesses.
For example, if your financial year ends on 31 December, your CT1 Return is due by 31 September the following year. Revenue sends a unique Notice of Filing Requirement to each company, specifying your exact deadline. Missing this triggers automatic late filing surcharges starting at €300, escalating with further delays.
Preparation begins with finalising your financial statements, including the profit and loss account and balance sheet. Your accountant then creates the tax computation, adjusting for timing differences, disallowed expenses, and reliefs like R&D credits or startup relief.
The form itself captures summary figures, with supplementary pages for detailed schedules on income, charges, and foreign activities. Most companies file electronically via Revenue's ROS system, uploading signed director approvals and any required attachments like computations.
Small companies often qualify to file abbreviated versions without full audited accounts, but all must include director signatures confirming the information's accuracy. Professional review minimises errors that could lead to Revenue queries or penalties.
Late filing incurs surcharges of €300 for one to three months overdue, €500 for three to six months, and €1,000 beyond six months. These penalties apply even if no tax is due, compounding with tax interest on any unpaid liability at 0.0219% per day.
Persistent lateness risks Revenue audits, director personal liability, and restrictions on tax clearance certificates needed for grants or tenders. It also jeopardises audit exemptions for qualifying micro companies, increasing future compliance costs significantly.
Yes, every company chargeable to Irish corporation tax must file a CT1 Return annually, including dormant companies with nil activity. Even if your business reports losses or claims full reliefs, submission confirms your tax position and maintains compliance.
Newly incorporated companies file their first CT1 for the initial accounting period, potentially shortened or extended up to 18 months. Non-residents trading in Ireland also file CT1s, ensuring Revenue receives complete records for all taxable entities.
Non-audit exempt companies must attach signed financial statements and director reports. All filers provide tax computations, with larger entities submitting additional schedules for group relief or foreign income.
Electronic filing via ROS requires PDF attachments where needed, authenticated by director PINs. Retain copies and supporting workings for six years, as Revenue can request them during compliance checks.
The CT1 Return focuses on tax, whilst CRO annual returns require abridged accounts. However, both draw from the same financial year end data, so aligning your compliance calendar prevents duplicated effort and missed deadlines.
Late CT1 filings do not directly impact CRO status but signal poor governance during investor due diligence, potentially affecting funding or valuations.
Yes, you can submit amendments within statutory time limits, typically four years from the filing deadline. Use Revenue's amendment process via ROS, providing revised computations and explanations for changes.
Amendments often arise from error corrections or additional relief claims discovered post-filing. Whilst possible, frequent amendments raise red flags for Revenue interventions.
