Money Matters

Self-assessment tax return: A guide on how to complete it (update for 2024/2025)

Discover the steps to take to file your self-assessment tax return (Form 11), including info on registering, tax calculations, and surcharges to be aware of.

The deadline for filing your self-assessment tax return is looming. Yes, it’s that time of year again if you’re self-employed. 

The official deadline is 31 October 2025—but it can be extended if you use Revenue’s Pay and File system to both pay and file through ROS (Revenue Online Service). 

The extended Pay and File deadline is 19 November 2025. 

The deadline for postal returns is also 31 October. But Revenue has now made online filing mandatory for most categories of taxpayers, with very few exceptions. So that’s really a moot point. 

To help you along the way when it comes to filing your tax return, read this guide for tips on registering for self-assessment and submitting your return. 

It also covers common mistakes to be aware of, and how using cloud accounting software can help you stay on top of you numbers—therefore making the self-assessment process a smooth one. 

Here’s what we cover in this article:

How to register for self-assessment

But first things first. How do you register? Follow these 3 steps:

Step 1: Get your ROS Access Number

Firstly, you have to apply at revenue.ie on for your ROS Access Number (RAN), which will be sent out to your postal address. You will need your PPS number.

Alternatively, you can apply by post by completing form TR1.

Step 2: Get your digital certificate

Once you’ve received your RAN and Revenue has processed your application, you have to apply for your digital certificate. You do this by entering your RAN number at revenue.ie and answering all relevant sections.

A ROS system password will be sent to your postal address. Using this password, you can retrieve and download your digital certificate, which you should name and allocate a password to.

Step 3: Save your digital certificate and access Revenue Online Service (ROS)

Once you have retrieved your ROS digital certificate, you can access ROS to file your Form 11 tax return, pay your tax and view your account.

The registration process can take up to 10 business days, so you need to get moving if you’re not registered yet.

How to complete a self-assessment tax return

As the name implies, you’re responsible for assessing what tax you must pay, though ROS does the calculations for you, based on what information you input.

You can claim certain business expenses against tax, such as rent, lighting and heating, accountancy fees, and interest paid on business loans. These must be wholly and exclusively for the purpose of the trade.

Once you’re registered, you fill out a Form 11 online.

Your tax liability will comprise two elements:

• The balance of income tax payable from 2024.
• A preliminary tax liability for 2025.

The preliminary tax should usually be 90% of the current year liability although Revenue also accepts 100% of your previous year’s liability, or 105% of the liability from the year before that (if you’re paying by direct debit).

If this is your first year using self-assessment, preliminary tax is still due but, because there was no previous year, this will be ‘nil’. However, if you want to pay 90% of the current year’s tax then you can also do so.

Once you know your total liability, you make your payment via ROS.

Though you don’t have to submit any supporting documents such as invoices, bank statement and receipts, you need to keep them. Because if Revenue ever audits you, you’ll be expected to provide those documents.

By using good cloud accounting software, you’ll be able to store your records in one place and have everything ready for when you need to submit your self-assessment tax return.

Tax rates

Income tax rates for self-employed individuals are the same as those for PAYE workers.

If you’re a single person, the first €44,000 is taxed at 20% and the balance is taxed at 40%.

If you’re married or in a civil partnership with one income, the first €53,000 is taxed at 20% and the balance at 40%.

If you’re married or in a civil partnership with two incomes and doing a joint assessment, it’s a little more complicated. For two incomes, each person gets a standard rate band and it can be transferable up to a maximum amount between spouses or civil partners of €35,000. This allows up to €77,000 to be taxed at the lower 20% rate between the couple, depending on their earnings.

You also have to pay USC (Universal Social Charge) and PRSI (Pay Related Social Insurance) on top of your tax liability and these are both charged on your gross income.

Some good news for the self-employed is that since 2016, self-employed workers are entitled to an Earned income Tax Credit.

The Earned Income Tax Credit is €2,000 for this year’s tax returns, which is the same as the PAYE credit. 

Once your tax has been calculated, ROS subtracts your tax credit to reduce the amount you actually have to pay.

Read more about self-assessment

• Self-assessment expenses you can claim on your tax return
• 10 top tips for filing your self-assessment tax return

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Common self-assessment mistakes

Rory Coll, who runs a long-established accountancy practice, Coll & Co, in Galway, outlines a couple of the common pitfalls self-assessed taxpayers make when completing their returns.

One is in relation to the Local Property Tax (LPT).

He says: “One particular trap to watch out for is that although you may file your income tax return on time, your LPT may not be up to date.

“If that is the case, Revenue may apply up to a 8% surcharge to your income tax return which may be quite penal, as it then considers all your filings are late.”

Another potential banana skin is around mileage and travel expenses.

Rory adds: “Self-employed business owners may think that they can claim mileage and overnight allowances at civil service rates, but this is only available to employees.

“The self-employed can claim for only receipted expenses.”

Penalty for late filing

A late-filing surcharge is added to the tax due. If your tax return is submitted within two months of the submission deadline, the surcharge will be 5% of the tax due (excluding preliminary tax).

If it’s filed more than two months after the submission deadline, the surcharge will be 10% and, in addition, interest will be charged on the tax due at a rate of approximately 10% per annum.

But perhaps even more worrying than a financial penalty is that if you’re late filing your tax return, it could potentially trigger  Revenue to carry out a tax audit on your financial affairs because timely filing is one of the indicators used in Revenue’s risk profiling systems—and that’s not something you’d want to invite upon yourself. 

Final thoughts: Don’t leave filing your tax return too late

A final word of advice—don’t leave filing your tax return to the very last minute. 

On deadline day, ROS could slow down because many of the other around 700,000 self-assessed taxpayers are trying to log in.

So give yourself the time to make sure your numbers are correct, you have the required information to hand and you file your self-assessment tax return in plenty of time.

Editor’s note: This article was first published in October 2019 and has been updated for relevance.