Preliminary Tax in Ireland: Deadlines and Payment Rules from Revenue

Preliminary tax is the advance payment that Revenue expects towards a tax bill before the final figure is known. For companies it is preliminary corporation tax (CT); for self-assessed individuals it is preliminary income tax. This guide sets out the deadlines and payment rules as they appear on Revenue's own pages, with the date each page shows, so finance teams and business owners in Dublin and elsewhere can check their diary. Preliminary tax is a Revenue obligation and is separate from the Companies Registration Office annual return, which we cover in our guide to the CRO annual return and Form B1.

One caution before the detail: percentages, thresholds and dates can change from year to year. Everything below reflects the pages as read at the time of writing. Check the current Revenue page on the day you make a payment.

Preliminary corporation tax: the basic structure

According to Revenue's page "When is preliminary Corporation Tax (CT) due?" (published 1 October 2025), the rules depend on the size of the company's previous liability and the length of the accounting period. The page distinguishes between large companies and small companies.

Large companies

The page says large companies can pay their preliminary CT in two instalments when the accounting period is longer than seven months:

• First instalment: due on the 23rd of the sixth month of the accounting period. It is either 50% of the CT liability for the previous accounting period or 45% of the CT liability for the current one.
• Second instalment: due on the 23rd of the eleventh month. It brings the preliminary tax up to 90% of the final tax due for the current accounting period.
• Short periods: if the accounting period is less than seven months, the company must pay 90% of the preliminary tax in one instalment.

Small companies

Revenue says small companies must pay their preliminary tax in one instalment if they had a CT liability of less than €200,000 in their previous accounting period. The payment must be made 31 days before the end of the accounting period, and before the 23rd of that month.

The page does not define "large" beyond contrasting it with the small-company test, so a company close to the €200,000 line should read the page itself or take advice. For new companies, payment methods and interest, check Revenue's other pages.

Paying and filing: the balance and the return

Revenue's "Corporation Tax (CT) payment and filing" page (published 1 October 2025) covers what happens after the preliminary payment. A company must use the Revenue Online Service (ROS) to file its return and pay any tax due. The page describes the steps in ROS for paying preliminary tax: sign in, go to the payments and returns area, choose Corporation Tax, then make a payment and select the period (or make a nil declaration). If the period you need is not listed, the page says to use MyEnquiries to open a new CT period before making the payment, because the payment may be refunded if it is applied to an earlier period.

For the balance, the same page says the company must complete and file a CT1 form and a 46G form (Company) by the return filing date, and pay any balance of tax due by that date. The filing and payment deadline is nine months after the end of the accounting period, and the payment must be made on or before the 23rd of the ninth month.

Interest and surcharges

The same page states that interest is due at a daily rate of 0.0219% on late payments, or payments not made in full, and that you cannot appeal an interest charge to the Tax Appeals Commission. For late returns, it lists a surcharge of 5% of the tax due (up to a maximum of €12,695) if filed within two months of the filing date, and 10% (up to a maximum of €63,485) if filed more than two months after the filing date. It also says late filing restricts certain claims, namely excess capital allowances, loss relief and group relief. These figures are as shown on the page at the time of writing and may be updated.

Preliminary income tax for self-assessed individuals

Revenue's page "What is preliminary tax?" (published 9 December 2025) covers individuals who pay tax under self-assessment. It states: "You must pay this by 31 October of the tax year in question." The amount paid must be at least the lowest of three figures:

• 90% of the tax due for that tax year;
• 100% of the tax due for the immediately previous tax year; or
• 105% of the tax due for the tax year before the immediately previous one. The page limits this option to people paying by direct debit, and says it does not apply if the tax for that earlier year was nil.

The page lists payment through ROS (a ROS Debit Instruction from a bank account, or debit or credit card), through myAccount (a once-off Single Debit Instruction), or by direct debit, and says only VISA and MasterCard cards are acceptable. The direct debit option is set up online through ROS. The page does not mention any ROS deadline extension, so any extended date in a given year would need to be confirmed on Revenue's announcements for that year.

First year in self-assessment

Revenue says a payment of preliminary tax may not be required for the first year you are a self-assessed taxpayer. It describes two options: pay 100% of the previous year's liability (usually nothing, since that liability is normally nil), or pay 90% of the current year's tax, which reduces the amount due the following year.

Underpayment

The page warns that you must make sure you do not underpay preliminary tax, or you may be charged interest, and that interest runs for each day (or part of a day) past the deadline. It does not give the rate in the text read for this article.

A quick comparison

A practical approach for finance teams

The points below are our suggestions, not Revenue requirements.

• Diary the dates from the accounting period. For companies, the instalment dates move with the year-end. Put the sixth-month and eleventh-month dates, and the nine-month balance date, in the finance calendar when the year-end is set.
• Record the basis used. Keep a short note of which calculation you relied on (for example, previous-period liability or current-period estimate) and the working behind it. This helps if the figures are queried later.
• Forecast profit during the year. The 90% test refers to the final tax for the current period, so a rolling forecast helps avoid a large shortfall at the balance date.
• Check ROS access. Make sure at least two people can sign in and pay, and that any new period has been opened before the payment date.
• Brief the board. Tax deadlines are worth a standing line in board packs. Our overview of directors' duties under Irish company law explains the wider framework.

What these pages do not tell you

Revenue's pages are written for the general case. The income tax page does not give the interest rate in the text we read. Neither page replaces professional advice for groups, companies with unusual accounting periods, or anyone claiming reliefs that affect the liability. If your situation is not covered, check Revenue's Tax and Duty Manuals or speak to a tax adviser.

Learnsignal's offices are off Baggot Street in Dublin, and we offer in-person training from there. For current details, see our CPD pages.

Frequently asked questions

When is preliminary tax due for a small company?

Revenue's page says a small company with a CT liability below €200,000 in its previous accounting period pays in one instalment, 31 days before the end of the accounting period and before the 23rd of that month.

When must self-assessed individuals pay preliminary income tax?

Revenue's page says you must pay by 31 October of the tax year in question. It lists the lowest of 90% of the current year's tax, 100% of the previous year's tax, or (for direct debit payers) 105% of the tax for the year before that.

Do large companies have to pay in two instalments?

Revenue says large companies can pay in two instalments when the accounting period is longer than seven months. If the period is shorter, the page says 90% must be paid in one instalment.

What happens if I underpay?

Revenue says interest may be charged on underpaid preliminary tax. For corporation tax, the payment and filing page gives a daily rate of 0.0219% on late or part payments. Check the current page for any change.

Where can I check the current rules?

Use the pages on revenue.ie headed "When is preliminary Corporation Tax (CT) due?", "Corporation Tax (CT) payment and filing" and "What is preliminary tax?", and check their dates before relying on them.

Preliminary tax rules reward early planning, so confirm the dates for your own year-end and tax year and check Revenue's pages again when you make each payment.