Ireland CT Preliminary Payment 2026: January Deadline Guide for SMEs
CT Preliminary Tax Ireland deadlines arrive quickly each January, catching many SMEs off guard. For companies with February year-ends, the preliminary Corporation Tax payment due on 23 January 2026 often falls before final accounts are ready.
If a company misses or underpays this payment, Revenue may charge interest, apply surcharges, and increase scrutiny. However, there is still time to review your position and take action now.
This guide explains what Irish SMEs need to know, who must pay preliminary Corporation Tax in January, how the payment is calculated, and what practical steps you can take to avoid penalties while time remains.
What Is Corporation Tax Preliminary Payment?
Corporation Tax preliminary payment is an advance payment of your company’s Corporation Tax liability for the current accounting period. It is mandatory and applies even where final accounts are not yet complete.
Revenue requires companies to pay preliminary tax before the end of their accounting period, or shortly after, depending on the year-end date.
In practice, this means companies must estimate their Corporation Tax liability and pay it in advance, rather than waiting until the final CT return is filed.
Who Must Pay Preliminary Corporation Tax in January?
January preliminary Corporation Tax payments mainly affect companies with February year-ends.
This typically includes:
- SMEs with accounting periods ending 28 February
- Owner-managed companies
- Trading companies and investment companies
- Companies that were profitable in the current or prior year
If your company falls into this category, the deadline to pay preliminary Corporation Tax is 23 January 2026.
Key January 2026 Corporation Tax Deadlines
Understanding the dates is critical.
For Companies with a 28 February Year-End
- 23 January 2026 – Preliminary Corporation Tax payment due
- 23 November 2026 – Balance of Corporation Tax due and CT1 return filing
These deadlines apply even if your year-end accounts are not finalised by January.
How Much Preliminary Corporation Tax Must Be Paid?
The amount you must pay depends on whether your company is treated as a small company or a large company for Corporation Tax purposes.
Small Companies
A company is generally treated as small where its Corporation Tax liability for the previous accounting period does not exceed €200,000.
Small companies can choose to pay:
90% of the final Corporation Tax liability for the current period, or
100% of the Corporation Tax liability for the previous period
This option provides flexibility, particularly where profits are broadly consistent year to year.
Large Companies: Two Instalment Preliminary CT Rules
Companies that do not meet the small company criteria are treated as large companies for Corporation Tax purposes.
Large companies must pay preliminary Corporation Tax in two instalments, both based on the current year’s estimated liability.
How the Two-Instalment System Works
First instalment
Due six months into the accounting period
Must equal 50% of the current year’s estimated Corporation Tax liability
Second instalment
Due one month before the end of the accounting period
Brings total preliminary payments to 90% of the estimated annual liability
The remaining balance is paid when the final CT return is filed.
Unlike small companies, large companies cannot rely on the previous year’s liability, which makes accurate forecasting essential.
Why This Matters for Larger Companies
Underpaying either instalment can lead to:
Daily interest on the shortfall
Increased Revenue scrutiny
Cashflow pressure later in the year
For this reason, early review of trading results and forecasts is critical, especially where profits fluctuate.
Why January Preliminary CT Causes Problems for SMEs
January can be a difficult time for SMEs to estimate Corporation Tax accurately.
Common challenges include:
Accounts not yet finalised
Year-end adjustments still in progress
Uncertainty around provisions, stock, or accruals
Directors assuming tax can wait until later in the year
However, Revenue does not accept “accounts not ready” as a reason for missing or underpaying preliminary tax.
What Happens If You Underpay or Miss the January Deadline?
Failing to meet the January preliminary Corporation Tax requirement can trigger several consequences.
Interest
Revenue charges interest daily on underpaid Corporation Tax from the due date.
Surcharges
Late or incorrect payments may result in surcharges on the final Corporation Tax liability.
Increased Revenue Scrutiny
Repeated issues with preliminary tax increase the likelihood of Revenue queries or compliance checks.
In most cases, these costs far exceed the effort involved in reviewing the position early.
Practical Steps SMEs Should Take Now (January 3 Checklist)
As of now, there is still time to act. Practical steps include:
- Review current year trading results
Look at management accounts, margins, and year-to-date profits. - Compare with last year’s Corporation Tax liability
This may be used as a safe reference point for small companies. - Identify any unusual items
One-off income, exceptional expenses, or asset disposals can distort estimates. - Confirm cashflow availability
Ensure funds are available ahead of the 23 January deadline. - Get advice early
Small adjustments made now can prevent interest and penalties later.
How Preliminary Corporation Tax Fits with Other January Obligations
January is already a heavy compliance month for many SMEs.
Alongside preliminary Corporation Tax, businesses may also be managing:
VAT returns and payments
PAYE and payroll filings
Director year-end planning
Cashflow pressures after December
For this reason, early planning is far more effective than leaving Corporation Tax payments until the final week.
What This Means as We Move Further into 2026
Although this payment relates to the 2026 accounting period, decisions made now directly affect:
Cashflow for the coming months
Final Corporation Tax payable later in the year
Your overall compliance position with Revenue
Addressing preliminary Corporation Tax properly now reduces stress, protects cashflow, and avoids last-minute issues.
Frequently Asked Questions
What is preliminary Corporation Tax in Ireland?
Preliminary Corporation Tax is an advance payment of Corporation Tax that Irish companies must pay before filing their final CT return.
When is preliminary Corporation Tax due in January?
For companies with a 28 February year-end, preliminary Corporation Tax is due on 23 January.
Can I base my preliminary payment on last year’s tax?
Yes. Small companies can usually base their payment on the previous year’s liability.
What if my accounts are not finalised?
You can still estimate preliminary Corporation Tax using management accounts or forecasts and adjust later.
Does every company have to pay preliminary Corporation Tax?
Most active companies do, although newly incorporated or very low-liability companies may differ.
How We Can Help
At Richard OShea Consultancy, we support SMEs and owner-managed businesses with Corporation Tax planning and compliance, including:
Reviewing preliminary Corporation Tax calculations
Estimating liabilities where accounts are not yet finalised
Advising on the most appropriate preliminary payment option
Managing cashflow around January tax deadlines
Ensuring compliance while avoiding unnecessary overpayments
We also provide full support with Corporation Tax returns, from preliminary tax reviews to year-end filing and ROS compliance. Learn more about our Corporation Tax return services here: Corporation Tax returns
If you are unsure how much Corporation Tax your company needs to pay this January, or you want to sense-check your figures before the deadline, now is the right time to get advice. Contact us today to discuss your position.
Final Thoughts
January preliminary Corporation Tax deadlines arrive quickly, particularly for companies with February year-ends. Although it may feel early in the year, Revenue expects action now.
By reviewing your position in early January, you still have time to make informed decisions, avoid interest and surcharges, and start 2026 on a stronger footing.
If you would like help reviewing your Corporation Tax position or planning ahead, get in touch to discuss your situation.
This article is intended for informational purposes only and should not be considered a replacement for professional advice. The author(s) disclaim any liability for actions taken or not taken based on the content of this document. It is recommended to seek tailored advice before making any decisions related to the topics discussed in this article.
