Corporation Tax Ireland: CT1 Filing Checklist for Limited Companies

Preparing for Corporation Tax Ireland (CT1) doesn’t need to be overwhelming. With the right structure, early preparation, and professional guidance, Irish businesses can meet their obligations confidently and avoid unnecessary penalties.

At RizFin, we support limited companies across Ireland with clear systems for Corporation Tax compliance. This allows business owners to stay focused on growth, while we handle the detail of CT1 preparation and filing.

Filing your CT1 return correctly is not just about compliance. It’s about protecting your business’s reputation, maintaining financial health, and creating a foundation for sustainable growth.

Why Timely CT1 Filing Matters

For Irish companies, the Corporation Tax Ireland CT1 return must be filed electronically through Revenue Online Service (ROS).

• The deadline is nine months after the end of your company’s financial year

• But no later than the 23rd day of that ninth month

Examples:

• Year-end 31 December 2024 → deadline 23 September 2025

• Year-end 30 April 2025 → deadline 23 January 2026

Why filing on time is essential:

• Avoids surcharges of 5–10% of your tax liability

• Prevents daily interest charges on unpaid tax

• Ensures you don’t lose access to valuable reliefs (loss relief, group relief, etc.)

Preparing 4–6 weeks in advance gives your accountant time to review your records, resolve queries, and help you plan your tax position with confidence.

CT1 Deadlines at a Glance

Quick rule: Add 9 months to your year-end, then file on or before the 23rd of that month.

🔗 Related: Our Services keeps you compliant and stress-free.

Corporation Tax Ireland: What Documents Do You Need for Your CT1?

Organising your paperwork in advance makes the CT1 process smoother and less stressful. Below is a checklist of key documents we recommend preparing for your Corporation Tax Ireland filing.

1. Financial Records

The accuracy of your CT1 return starts with clean financial records. Gather:

• Income and expense reports from your accounting software

• Year-end bank statements

• Aged receivables (customer invoices)

• Aged payables (supplier bills)

• Loan balances and interest statements

• Inventory balances (if applicable)

🔗 Related: Our Bookkeeping Services keep your records accurate and up to date.

2. Payroll & Compliance

Payroll records form a key part of your overall tax compliance picture:

• Monthly payroll summaries and P30 submissions

• Confirmation of PAYE compliance through Revenue Online Service (ROS)

• Any staff reimbursements or directors’ drawings not yet recorded

🔗 Related: Discover how our Payroll Services keep you compliant.

3. Assets & Depreciation

Depreciation reduces your taxable profits, so clear records are important:

• Asset register (equipment, software, furniture, etc.)

• Purchase dates and original costs

• Records of disposals (sold, donated, written off)

• Lease agreements or financing details

4. Director & Shareholder Information

Up-to-date records on directors and shareholders support accurate tax reporting:

• Dividends paid or declared during the year

• Directors’ salaries and outstanding expenses

• Changes to officers or shareholders

• Related party transactions that need disclosing

5. Additional Considerations

Other factors can affect your CT1 filing:

• Grants, loans, or funding received

• Changes filed with the CRO (address, share capital)

• Unusual or one-off events (asset sales, restructuring, loss write-offs)

• Previous CT1 filings (if you’ve changed accountants)

Submitting Your CT1 Documents Securely

At RizFin, we provide a secure, encrypted client portal for submitting sensitive documents:

Upload securely via our Client Portal

Early submission allows time for thorough checks, queries, and adjustments — all part of ensuring your return is correct and compliant.

Ready to Prepare for Your Corporation Tax Ireland Return?

Avoid the last-minute rush. Book your free discovery call with RizFin today. We’ll walk you through your Corporation Tax Ireland preparation, ensuring your CT1 return is accurate, compliant, and submitted on time.

Trusted External Resources

For further guidance on Corporation Tax Ireland, we recommend referring to these trusted sources:

• 🔗 Revenue Ireland: Corporation Tax for Companies

• 🔗 Revenue Ireland: Form 46G Guidance

These pages provide essential information on Revenue obligations, deadlines, and compliance requirements.

Final Thoughts

Getting your Corporation Tax Ireland return right is about more than ticking a box. It’s about protecting your business from unnecessary costs, staying compliant with Revenue, and maintaining control over your company’s financial health. By preparing early and working with trusted professionals, you can avoid stress, meet your deadlines, and stay focused on what matters most — growing your business.

If you need expert guidance on CT1 filings or Corporation Tax compliance, RizFin is here to help.