Your certificate of incorporation feels like the finish line. It is actually the starting gun. From the day the Companies Registration Office (CRO) issues your company number, both the CRO and the Revenue Commissioners start counting, and the deadlines land faster than most first-time directors expect.
This guide covers the 8 key dates every newly formed limited company in Ireland should have in the diary, and what it costs to miss each one. Still at the company formation stage? Read our guide on how to set up a company in Ireland, or the Citizens Information step-by-step guide to setting up a business, first.
What are the 8 key dates at a glance?
The table below assumes the standard private company limited by shares; each date is explained in detail afterwards.
|
# |
Deadline |
What happens |
|
1 |
Within 4 weeks of starting to trade |
Register for Corporation Tax with Revenue |
|
2 |
Within 5 months of incorporation |
File beneficial ownership details with the RBO |
|
3 |
6 months after incorporation |
First B1 annual return to the CRO |
|
4 |
Before turnover approaches the threshold |
VAT registration with Revenue |
|
5 |
Before your first pay run |
Register as an employer for PAYE |
|
6 |
31 days before the accounting period ends |
Preliminary Corporation Tax payment |
|
7 |
Every 12 months from your ARD, plus 56 days |
Annual return with financial statements attached |
|
8 |
Day 23 of the 9th month after year end |
File the CT1 and pay the Corporation Tax balance |
1. When must you register for Corporation Tax?
Corporation Tax is usually the first tax a new company deals with. Revenue expects you to register for Corporation Tax within four weeks of starting to trade. Note the trigger: trading, not incorporation. A dormant company has no Corporation Tax deadline yet.
The tax registration happens online through Revenue Online Service (ROS), usually via your accountant. Paper routes still exist; see our guide to filling out the TR2 form if that applies.
2. When must you file with the Register of Beneficial Ownership?
Every company must file details of its beneficial owners, meaning anyone who owns or controls more than 25% of it, with the Central Register of Beneficial Ownership (RBO) within 5 months of incorporation. You will need:
- Each owner's name, date of birth, nationality and residential address.
- Their PPS number, or a verified BEN2 form where they do not have one.
- The nature and extent of the control each person holds.
Non-filing is a criminal offence, with fines of up to €500,000. Banks also check the register before opening accounts, so a missing filing stalls your banking first.
3. When is your first B1 annual return due?
Your first annual return falls due exactly 6 months after incorporation, and no financial statements are needed with it. The Form B1 confirms your company details; you get 56 days from the annual return date to file it through CORE, the CRO's online filing portal.
Treat it seriously anyway: this first filing fixes your ARD, the date your return falls due every year afterwards.
4. When do you need to register for VAT?
VAT registration is triggered by turnover rather than by the calendar. Since 1 January 2025, Revenue's registration thresholds are €42,500 for services and €85,000 for goods in any continuous 12-month period, and the same figures apply in 2026. Register before you cross the line, not after.
Watch the pipeline, not just the invoices already issued. Our breakdown of the VAT thresholds in Ireland also covers voluntary registration, which can suit B2B businesses. Once registered, expect a VAT return every two months as standard.
5. When should you register as an employer?
Before anyone gets paid. If your company will pay a salary to staff, or to you as a director, you must register as an employer with Revenue first. Irish payroll runs on real-time reporting, so each payment is reported on or before payday.
There is no grace period. Founders regularly pay themselves in month one and register in month three. An outsourced payroll service removes that risk.
6. When is preliminary Corporation Tax due?
For small companies, preliminary Corporation Tax falls due 31 days before the end of the accounting period, paid by day 23 of that month. Helpfully, a startup whose first-period Corporation Tax bill is under €200,000 pays no preliminary tax for that period; everything is paid when the return is filed.
From year two, diarise it: interest on underpaid preliminary tax accrues daily and is applied automatically.
7. When are your annual return and financial statements due each year?
After the first return, the B1 falls due on your ARD every 12 months, with the same 56-day filing window. From the second return onwards, financial statements must be attached. These are filing obligations under the Companies Act 2014, and the CRO enforces them without sympathy: a late filing penalty of €100 the day the window closes, then €3 per day up to €1,200.
The bigger danger is that you lose your audit exemption. Two years of mandatory audits cost far more than the late fee. Our year-end accounts and B1 filing service works backwards from the ARD so the window never sneaks up.
8. When is the CT1 Corporation Tax return due?
Your corporation tax return, the Form CT1, must be filed and paid by day 23 of the ninth month after your financial year-end date. In practice that is eight months and 23 days: a company with a 31 December 2025 year end will file and pay through ROS by 23 September 2026.
Most Irish companies choose 31 December so the financial year matches the calendar year. Decide deliberately, because this one year end date drives your CT1 and preliminary tax dates for the life of the company.
What else do new directors ask about key filing dates?
What happens if you miss the B1 deadline?
Late filing penalties start at €100 and grow by €3 a day to a cap of €1,200, and persistent non-filing can lead to strike-off. The harsher cost is losing the audit exemption for two years.
Do single-director companies need an RBO filing?
Yes. The register applies to nearly all Irish companies regardless of size. If you hold 100% of the shares, you are the beneficial owner, and your details must be filed within 5 months of incorporation like everyone else's.
Can you change your financial year-end later?
Usually, though the Companies Act 2014 generally limits limited companies to one change every five years. Check the knock-on effects on your accounting period and your CRO dates with an accountant before committing.
Do directors have to file personal tax returns too?
Most proprietary directors must file a Form 11 under self-assessment each year, separate from any tax returns the company files. It often surprises owners of new companies, so confirm your position early.
What should you do next?
Build the calendar now, while the company is young and the dates are few. Three early moves make every deadline easier:
- Set reminders 30, 14 and 7 days before each date above, and give your company secretary or accountant ownership of the list.
- Put bookkeeping services in place from day one, because every filing above depends on up-to-date records.
- Choose your financial year end deliberately rather than letting it default.
Business owners who hand this calendar over rarely regret it; tracking filing deadlines is what we do all day. If you would rather avoid penalties and never think about the ARD again, book a consultation and get in touch today.
Disclaimer: This guide is for general information purposes only and does not constitute professional advice. Speak to a qualified accountant about your specific circumstances before acting on anything covered here.