Week 1 PAYE: why a take-home estimate can differ from payroll

What the guidance explains

Week 1, also called Month 1 for monthly pay, treats each pay day separately. Unused credits and bands from earlier periods are not carried forward. Cumulative payroll instead considers pay and tax since the start of the year.

Revenue’s employee guidance was published on 31 August 2026. This article reviews that guidance; the publication date does not mean Week 1 taxation began on that day.

Who should pay attention

Employees comparing an indicative calculator result with a payslip should check the tax basis on their certificate. Employers follow the basis specified on the RPN. Missing prior-employment information or a change in credit allocation can affect which basis is used.

A Week 1 employer cannot refund earlier Income Tax or USC until a cumulative certificate is issued. Revenue explains the year-end return route for employees who remain on Week 1.

Try a learning example

Suppose this period’s gross PAYE is €80 and available period credit is €76.92: tax after credit is €3.08. If gross PAYE is €50 with the same credit, tax is zero; the leftover credit does not generate a Week 1 refund. This example covers PAYE only, excluding USC and PRSI.

Use the PAYE Lab to compare period and cumulative exercises. The homepage estimates a salary on annualised week-1 assumptions; it does not retrieve a live RPN or reproduce every payroll adjustment.

Official sources

• Revenue — starting your first job, Week 1 basis (31 August 2026)
• Revenue — employer Week 1 method and worked examples
• Revenue — basis of taxation

Try the related tools

• Practise period and cumulative PAYE
• Follow the payroll lessons
• Read estimate limitations