Ireland ROS September Week One: PAYE, VAT and CT1 After IOSS
As of 1 September 2026, Irish SMEs should treat week one of September as ROS prep week after July IOSS cleared yesterday — August PAYE on 14 September, bi-monthly VAT on 19 September, and CT1/RCT through 23 September.
Revenue’s Calendar of key dates for tax professionals sets September’s Irish SME ROS rhythm: PAYE/PRSI/USC/LPT for August on 14 September (payment extended to 23 September for ROS users who file and pay online), a dense VAT 3 cluster on 19 September including July–August bi-monthly returns, and Corporation Tax plus RCT obligations through the 23rd. As of Tuesday 1 September — with July IOSS cleared yesterday — protect week-one prep slots before mid-month leave thins coverage.
Treat August IOSS (due 30 September) as a separate month-end track that must not steal the September PAYE and VAT prep slots. Domestic VAT 3 and IOSS never replace each other.
Sequence from this week through late September
1–7 September — lock August payroll runs, reconcile July–August sales and purchase ledgers, and start iXBRL / Form 46G gathering for December year-end CT1.
14 September — August PAYE monthly return (and DWT/PSWT where due); ROS payment extension to 23 September only if you file and pay online.
19 September — monthly August VAT 3, bi-monthly July–August VAT 3, four-monthly May–August, and annual cycles ending in August, plus Return of Trading Details where required.
1–23 September — CT1 and corporation tax balance for December 2025 year-ends under mandatory e-filing; RCT monthly return for August on 23 September. Diary 30 September for August IOSS so July’s close-out does not cascade.
September week-one checklist
Confirm July IOSS cleared yesterday — chase any stranded payments before week-two payroll close.
Lock August payroll runs and employee changes before mid-September leave thins coverage — the 14 September return date is thirteen days away.
Reconcile July and August sales and purchase ledgers for the bi-monthly VAT pack while July ROS cash journals are still fresh.
Start iXBRL and Form 46G gathering for December year-end CT1 so validation is not a 22 September surprise, and confirm ROS digital certificates for the late-September cash days.
How FinnAccountings helps through September ROS
Organised books make multi-deadline ROS months easier to review. FinnAccountings helps Ireland and UK businesses prepare bookkeeping, payroll, and tax packs with Chartered Accountant insight before you or your Chartered Accountant (Ireland) or ICAEW/ACCA adviser files. Start a free trial for review-ready drafts — we prepare records; we do not file ROS returns or make Revenue payments on your behalf.
Related reading
Yesterday’s after-IOSS September lock still maps the full ROS sequence.
August PAYE has twelve days to the 14 September return as of the 2 September midday brief.
December year-end CT1 has twenty-one days to 23 September as of the 2 September midday brief.
Bi-monthly July–August VAT has seventeen days to 19 September as of the 2 September midday brief.
Sources & references
This article draws on official guidance from the sources below.
- Calendar of key dates for tax professionals
Revenue (Irish Tax and Customs) · Accessed 2026-09-01 - Corporation Tax (CT) payment and filing
Revenue (Irish Tax and Customs) · Accessed 2026-09-01 - When VAT becomes payable
Revenue (Irish Tax and Customs) · Accessed 2026-09-01
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