Methodology

Plainly.ie is built for PAYE employees in Ireland — people employed under the Pay As You Earn system paying Class A PRSI. It does not cover:

• Self-employed income (Class S PRSI, Form 11)
• Benefits in Kind (company cars, health insurance)
• Rental income or investment income
• Auto-enrolment (My Future Fund) — treatment not yet confirmed by Revenue
• Married two-earner households (coming later)

All calculations use 2026 tax year rates sourced from Revenue.ie. Where possible, rates are loaded from a live database — JSON fallbacks are used if the database is unavailable.

Income Tax is calculated on taxable income (gross salary less pension contributions) at the standard rate (20%) up to the standard rate band, and the higher rate (40%) above it. Standard rate band thresholds: €44,000 for single individuals, €53,000 for married one-earner couples.

Tax credits applied automatically: Personal Credit (€2,000) and PAYE Credit (€2,000) for single individuals. Married one-earner couples receive an additional Married Credit. The Home Carer Credit (€1,950) is optional.

USC is calculated on gross salary (pension contributions do not reduce USC). Rates follow the 2026 bands: 0.5% up to €12,012; 2% on €12,013–€27,382; 3% on €27,383–€70,044; 8% above €70,044. The USC exemption threshold is €13,000.

PRSI is Class A at 4.2% on gross salary. The weekly exemption threshold of €352 and the tapering rule (€352–€424) are not currently modelled — annual figures are used directly. Taper relief is being reviewed (#26).

Pension contributions reduce taxable income for income tax purposes only. They do not reduce USC or PRSI. Age-related Revenue limits are disclosed in the UI but not enforced — a future update will cap contributions by age band.

The refund estimator checks seven relief categories against Revenue's rules for tax years 2022–2025. All estimates assume the user's stated marginal tax rate (20% or 40%) applies uniformly to all unclaimed relief — actual refunds may differ if circumstances changed across years.

Flat Rate Expenses — 20% of the published Revenue allowance for the selected occupation. Allowance amounts are sourced from Revenue's flat rate expense schedule but have not been individually verified against the current published list (#35). Verify your exact allowance at Revenue.ie before filing.

Rent Tax Credit — Credit amounts are fixed historical figures per person: €500 in 2022, €750 in 2023, €1,000 in 2024, €1,000 in 2025. Doubled for couples. The tenancy must be registered with the RTB. The 2022 and 2023 amounts reflect the retroactive increases applied under Budget 2024.

Remote Working Relief — 30% of estimated qualifying home costs at the marginal tax rate. Home costs are estimated at €4/day (broadband and utilities). This is a conservative estimate — actual qualifying costs may be higher. Revenue accepts the actual cost when filing in myAccount.

Medical Expenses — 20% of unreimbursed qualifying costs: GP visits, consultant fees, hospital charges, physiotherapy, and prescribed medication. Routine optical expenses (glasses, contact lenses) do not qualify. Proof of expenditure is required.

Non-Routine Dental — 20% of qualifying treatments: crowns, root canals, orthodontics, implants, bridges, and veneers. Routine check-ups and fillings do not qualify. A Form Med 2 from your dentist is required.

Third-Level Tuition Fees — 20% on fees above the €3,000 per-course disregard per year, for approved colleges in Ireland and the EU. Repeat students may be subject to a separate disregard — not currently modelled.

Dependent Relative Credit — €305 flat credit per year for qualifying dependants. This figure is the last confirmed Revenue amount and requires verification for the 2026 tax year (#33).

Not yet covered: Pension AVCs, income protection insurance premiums, PRSI overpayment recovery. These will be added in a future release.

Spending allocations are based on the Revised Estimates for Public Services 2026, published by the Department of Public Expenditure, NDP Delivery and Reform. Shares represent the proportion of gross current expenditure by Vote group. Capital expenditure is included.

The allocations have not been independently verified against the published Estimates document (#39). The revenue data shown (total tax take used to contextualise spending) may reference 2025 outturn figures — this is under review (#40).

All figures are estimates only. They do not account for mid-year income changes, multiple employments, non-PAYE income, Revenue adjustments, or individual circumstances that may affect your actual tax position.

No data entered on Plainly.ie is stored, transmitted, or retained. All calculations run in your browser.

If you notice an error or have a question about a specific calculation, please open an issue at github.com/eoghanomuiris/plainly.