Tax deductions
What tax deductions are in Ireland, which business costs are allowable, and how to claim them.
Published Friday 2 October 2026
Table of contents
Key takeaways
- A tax deduction, or allowable expense, is a business cost you subtract from your income to lower the income tax you pay in Ireland.
- Deductions and reliefs reduce the income you’re taxed on, while a tax credit reduces your final tax bill euro for euro.
- An expense is only allowable if it’s incurred wholly and exclusively for the business, so personal costs don’t qualify.
- You claim through the Revenue Online Service (ROS) on Form 11 if you’re self-assessed or Form CT1 for a company, with a Pay and File deadline of 31 October (18 November if you file and pay through ROS).
Tax deductions (definition)
A tax deduction, also called an allowable expense, is a business cost you subtract from your income to reduce the income tax you pay in Ireland. Revenue sets the rules for what counts.
You take your allowable expenses off your income, then pay tax on the lower taxable-income figure. So the more legitimate business costs you can claim, the less of your income is exposed to tax.
Example of a tax deduction calculation
A worked example shows how deductions lower the amount you’re taxed on. It also shows why the purpose of a cost matters.
Say Jo runs a photography studio and earns €77,000 in a year. She has €15,000 of deductible business expenses, which leaves taxable income of €62,000, so she pays tax on €62,000 rather than the full €77,000.
An expense only qualifies if it has a genuine business purpose. A new camera is deductible for Jo because she needs it for her work, but the same camera wouldn’t be deductible for a baker who has no business use for it.
Tax deductions vs tax reliefs and tax credits
Deductions and reliefs work differently from tax credits, and the difference changes how much you actually save. One reduces the income you’re taxed on, the other reduces the bill itself.
A deduction or relief reduces your taxable income, so its value depends on your tax rate: a €100 expense saves you €20 at the 20% rate or €40 at the 40% rate, as set out in Revenue’s rate-band thresholds. A tax credit reduces your final tax bill euro for euro, so a €100 credit lowers the tax you owe by €100 whatever rate you pay.
Common tax-deductible business expenses in Ireland
To be deductible, a cost must be directly related to running your business and incurred wholly and exclusively for the trade. Revenue sets out this test in its guidance on allowable business costs, and you can find wider help in our small business money guides.
These everyday categories are the ones small businesses claim most often:
- Rent, rates and premises utilities such as heating and lighting
- Staff wages and salaries
- Business travel and motoring costs
- Accountancy and other professional fees
- Advertising and marketing
- Business insurance
- Office equipment and supplies
- Business phone and broadband
Bigger purchases work differently. Assets such as equipment and vehicles are usually claimed over several years through capital allowances rather than deducted in full in the year you buy them.
Some costs can’t be claimed at all. Revenue doesn’t allow personal drawings, a sole trader’s own wages, ordinary commuting from home to work, or client entertainment.
Claiming for costs that are part business and part personal
Some costs cover both your business and your private life, and Revenue lists phone bills, motor expenses and rent as common examples. You can only claim the business share, so you need to apportion the cost fairly.
If you use your phone 80% for business, you claim 80% of the bill and treat the remaining 20% as personal. Keep your receipts and a record of how you worked out the split in case Revenue asks. The same approach applies when you’re running your business from a home office, where household costs are part business and part private.
How to claim tax deductions through Revenue
You claim your deductions when you file your tax return, so it helps to know the process and the deadline. If you’ve recently started out, you’ll first need to register as self-employed with Revenue before you can file.
The Pay and File deadline for the 2025 income tax return (Form 11) is 31 October 2026, with an extended deadline of 18 November 2026 if you both file and pay through the Revenue Online Service (ROS). Revenue publishes the up-to-date dates and rules for self-assessment in its return-filing guidance.
Follow these steps to claim through ROS:
- Sign in to ROS and open the return for the year you’re filing.
- Choose the right return: self-assessed individuals use Form 11, while companies use Form CT1.
- Enter your allowable business expenses in the relevant sections so they reduce your taxable income.
- Keep your records and receipts in case Revenue asks you to support the figures.
Keep on top of your deductible expenses with Xero
Tracking your costs as you go means your deductible expenses are ready when Pay and File comes around, with less last-minute admin. Xero captures and categorises your costs in one place, and its tools for expense claims keep everything organised for filing. Start today and get one month free.
FAQs on tax deductions
Here are quick answers to common questions about tax deductions in Ireland.
What’s the difference between a tax deduction and a tax credit?
A deduction lowers the income you’re taxed on, so its value depends on your rate. A credit reduces your final tax bill by the same euro amount no matter what rate you pay.
What business expenses are tax-deductible in Ireland?
Everyday running costs incurred wholly and exclusively for the trade, such as rent, wages, insurance and professional fees. Personal spending and ordinary commuting from home to work don’t qualify.
Can you claim an expense used for both business and personal use?
Yes, but only the business portion. Apportion the cost fairly and keep a record of how you split it.
How long do you have to claim a tax deduction?
Revenue applies a four-year limit, so you have four years from the end of the relevant tax year to claim expenses or a refund. You can read the detail in Revenue’s four-year rule.
Do you need receipts to claim tax deductions?
Yes, keep receipts and records to back up every claim, because Revenue can ask you to prove the figures on your return.
Related terms
Learn more about tax deductions
Handy resources
Advisor directory
You can search for experts in our advisor directory
Try Xero for free
Try Xero’s fast, simple, powerful online accounting software for your small business
Disclaimer
This glossary is for small business owners. The definitions are written with their requirements in mind. More detailed definitions can be found in accounting textbooks or from an accounting professional. Xero does not provide accounting, tax, business or legal advice.