Self-assessment tax return: A guide on how to complete it

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 2023 – 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 15 November 2023.

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
• How to complete a self-assessment tax return
• Tax rates
• Common self-assessment mistakes
• Penalty for late filing
• Final thoughts: Don’t leave filing your tax return too late

How to register for self-assessment

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

Step 1: Get your ROS Access Number

Firstly, you have to apply online on for your ROS Access Number (RAN), which will be sent out to your postal address.

Step 2: Get your digital certificate

Once you’ve received your RAN, you have to apply for your digital certificate. You do this by entering your RAN number on 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 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.

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 2022
• A preliminary tax liability for 2023.

The preliminary tax should usually be 90% of the current year liability.

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

Tax rates are the same as for PAYE workers.

If you’re a single person, the first €40,000 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 €49,000 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 but in principle, a married couple pays less tax than two single people, but not significantly less.

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.

This was introduced to in some way level the playing field with PAYE workers, who receive a PAYE tax credit of €1,775.

The Earned Income Tax Credit is €1,775 for this year’s tax returns.

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 10% 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 financial penalty is added to the tax due. If your tax return is submitted within two months of the submission deadline, the surcharge will be 5%.

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 – 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 700,000 approx 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.