Preliminary Tax Ireland — Self-Employed Guide
How to pay Preliminary Tax in Ireland.
Most self-employed workers get the amount wrong — and pay interest from October.
Preliminary Tax is a payment on account — an advance estimate of your current year's income tax, PRSI and USC, paid at the same time you file your prior year's Form 11. The deadline is 31 October each year. Get the amount wrong and Revenue charges interest automatically from that date. No notification. No warning. No grace period.
Ask us on WhatsApp — freeWhat Preliminary Tax actually involves
A Payment for the Current Year — Due Now
When you file your 2024 Form 11 in October 2025, you also pay Preliminary Tax for 2025 — income you are still earning. This means you are paying two tax obligations at once: the balance on last year, and an advance on this year. Many self-employed workers are unprepared for both payments arriving together.
Three Calculation Methods — Only One Is Safe
Revenue allows three methods: (1) 100% of the prior year's liability — the safest, no risk of underpayment; (2) 90% of the current year's estimated liability — requires an accurate projection of income still in progress; (3) 105% of the prior year's liability, if paying by direct debit. Method 1 is the standard choice for most clients.
What the Payment Covers
Preliminary Tax covers income tax, PRSI (Class S, 4%) and USC for the year in progress. Each component is calculated separately. If you underestimate any one of the three, the entire underpayment attracts interest. The calculation requires knowing your current year's income, your applicable tax credits, and the exact USC bands.
How to Pay — Through ROS
Preliminary Tax must be paid through Revenue's ROS system, linked to your Form 11 filing. You cannot pay it separately by bank transfer. If you do not have an active ROS account before October, you cannot file or pay on time. ROS registration takes up to 14 days including a postal step.
The Interest Trigger — Automatic from 31 October
Interest of 0.0219% per day accrues on any underpaid Preliminary Tax from 31 October — automatically. Revenue does not send a warning first. You discover it on your next tax statement, already accumulated. For a €2,000 underpayment, that is approximately €160 per year in interest alone.
The Prior Year Balance — Filed at the Same Time
The Form 11 deadline and the Preliminary Tax deadline are the same: 31 October (or mid-November via ROS). You must file last year's return, pay any balance on last year's tax, and pay this year's Preliminary Tax in a single ROS submission. Missing one component means missing all.
Common mistakes — and why they cost more than people expect
These errors appear consistently in self-managed filings. Each one results in automatic interest charges or an underpayment balance that compounds year to year.
Repeating last year's figure without adjustment
If your income increased this year, the prior year figure may be less than 90% of your current liability. Using 100% of last year is only safe if your income is stable. A significant increase means you owe interest on the gap.
Choosing the 90% method without a reliable projection
Estimating 90% of a current year not yet finished requires accuracy. Most self-employed workers underestimate because they project from their busiest months or forget seasonal variation. The interest starts from October — not from when the final figure is known.
Forgetting it is a separate payment from the Form 11 balance
Many first-year filers pay the balance on their prior year's Form 11 and consider themselves done. The Preliminary Tax for the current year is an additional payment in the same submission. Missing it means immediate interest from 31 October.
Not including PRSI and USC in the estimate
Preliminary Tax covers income tax and PRSI and USC. Calculating only on income tax understates the total. The shortfall on PRSI and USC attracts interest in the same way as income tax underpayment.
Paying the day after the deadline
One day late is still late. Interest starts on 1 November. There is no grace period. If the ROS extended deadline (mid-November) applies, that is the hard cut-off — not the end of November.
Assuming Revenue will notify you of underpayment
Revenue does not send a warning when you underpay Preliminary Tax. The interest accumulates automatically and appears on your next statement. By the time you notice, months of interest have already accrued.
What happens when Preliminary Tax is wrong or unpaid
- Interest of 0.0219% per day applies automatically to any underpaid amount — from 31 October, not from when Revenue identifies the shortfall. On €3,000 underpaid, that is around €240 per year.
- No advance warning. Revenue calculates the interest and adds it to your tax account. You see it on the next statement — already accumulated since October.
- If you also filed late, the 5% or 10% late filing surcharge is applied on top of the Preliminary Tax interest. Both run simultaneously.
- Consistent underpayment — across two or more years — can flag your file for a Revenue compliance review, including examination of your expense claims and income declarations.
- If you pay nothing, Revenue can issue an estimated assessment based on prior year data and begin enforcement proceedings without further notice.
Preliminary Tax requires an accurate income estimate before the year ends. Getting it right is a calculation problem — one that affects your cash flow for the year.
We calculate your Preliminary Tax as part of every Form 11 filing. We use the safest method for your situation, confirm the figure before filing, and ensure no interest accrues from October.
- We choose the calculation method that eliminates underpayment risk for your income level
- We factor in income tax, PRSI and USC together — no component is missed
- We include Preliminary Tax in the same ROS submission as your Form 11 — nothing filed separately
- We notify you of the total amount due before filing so there are no surprises on the deadline
- We communicate in Portuguese, Spanish, Italian and English — fixed fee of €350 for Form 11 including Preliminary Tax calculation
Clear pricing — no surprises
Fixed fees. Always confirmed before we start.
Need help calculating your Preliminary Tax?
Send us your details on WhatsApp. We calculate the correct amount, file your Form 11 and pay Preliminary Tax — all in one submission before the deadline.
Start on WhatsApp — it's freeFrequently asked questions
What is Preliminary Tax in Ireland?
Preliminary Tax is an advance payment of your current year's income tax, PRSI and USC. It is due on 31 October each year — the same date as your prior year's Form 11. The idea is that self-employed workers pay a portion of their tax for the year in progress, before the year ends and the final liability is calculated. The amount must be at least 100% of the prior year's liability, or 90% of the estimated current year liability. Underpaying triggers interest automatically from the deadline.
How do I calculate how much Preliminary Tax to pay?
There are three Revenue-approved methods. Method 1: pay 100% of the prior year's total liability (income tax + PRSI + USC combined). This is the safest option — if you pay at least this amount, no interest accrues regardless of what the current year's final bill turns out to be. Method 2: pay 90% of your estimated current year liability — requires a reliable income projection. Method 3: pay 105% of the prior year's liability, available only if paying by direct debit. We recommend Method 1 for most clients.
What happens if I underpay Preliminary Tax?
Interest of 0.0219% per day accrues automatically on the underpaid amount from 31 October. Revenue does not send a warning — the interest appears on your next tax statement, already accumulated. There is no grace period and no minimum threshold below which interest does not apply. If you also filed your Form 11 late, the late filing surcharge (5% or 10%) applies separately and simultaneously.
Can I pay Preliminary Tax in instalments?
Not through the standard ROS process. The full Preliminary Tax amount is due in a single payment on or before the filing deadline (31 October or the ROS extended date in mid-November). However, if you pay by direct debit through the Preliminary Tax Estimator on ROS, you can spread payments across the year — this also qualifies you for the 105% calculation method. This option works best when set up in January, not in October.
What is the Preliminary Tax deadline in Ireland?
The Preliminary Tax deadline is 31 October each year. If you file and pay through ROS, you get an extended deadline — typically the second or third week of November. For example, for the tax year 2025, the Preliminary Tax is due alongside your 2024 Form 11 by 31 October 2025, or by the ROS extended deadline (usually around 13 November 2025). Missing the extended deadline removes the extension — you are treated as if you filed and paid on the original 31 October date.
I did not pay Preliminary Tax last year. What should I do?
If you missed Preliminary Tax, interest has been accumulating since the October deadline. The first step is to file the overdue Form 11 if not already filed — this formalises the liability. The interest is then assessed and added to your account. The earlier you act, the less interest accumulates. Contact us before contacting Revenue — we can assess the total amount due, including interest, and file everything in one submission. Voluntary disclosure consistently results in lower total cost than waiting for Revenue to raise an inquiry.