Relevant Contracts Tax is one of the most frequently misunderstood compliance obligations for Irish trade contractors — and one of the most consequential when it goes wrong. Revenue has the power to make a principal contractor liable for the RCT that should have been withheld from subcontractor payments if the correct procedures were not followed. The penalties for non-compliance are real, and they are not limited to cases of deliberate evasion. Process failures — missing a notification, withholding the wrong rate, failing to file a deduction authorisation — create the same liability as intentional avoidance.
Most Irish trade contractors who use subcontractors understand that RCT exists. Far fewer have it embedded in their operational systems in a way that makes compliance automatic rather than something that depends on someone remembering to do it.
What RCT is and who it applies to
Relevant Contracts Tax applies to payments made by principal contractors to subcontractors in the construction, forestry, and meat processing sectors. For the vast majority of Irish trade contractors — builders, electrical contractors, plumbers, mechanical contractors, fit-out companies — the construction sector definition applies.
A principal contractor is any business that engages subcontractors to carry out relevant operations under a contract. If you hire a subcontractor to carry out any part of a construction project — whether it is a specialist trade or a general labour subcontract — you are a principal contractor for RCT purposes on that contract.
The RCT system is operated through Revenue Online Services (ROS). Subcontractors are assigned a deduction rate — 0%, 20%, or 35% — based on their tax compliance record. The principal contractor must withhold this deduction from each payment and remit it to Revenue.
The 4 steps of RCT compliance
Revenue’s RCT system requires four steps for every payment to a subcontractor:
- Contract notification. Before any payment is made under a new contract with a subcontractor, the principal contractor must notify Revenue of the contract via ROS. This registers the contract in the system and generates a contract number.
- Payment notification. Before each individual payment is made, the principal contractor must notify Revenue of the payment amount via ROS. Revenue responds in real time with a deduction authorisation, specifying the rate to be applied to that payment.
- Withhold and pay. The principal contractor withholds the specified deduction from the payment and remits it to Revenue, typically monthly via the RCT return. The subcontractor receives a net payment and a deduction authorisation document.
- File the RCT return. Monthly RCT returns summarise all payments made and deductions withheld during the period. These must be filed on time to avoid late filing surcharges.
Why managing RCT outside your operational system creates risk
The most common approach to RCT among Irish trade contractors is to manage it separately from the job management system. Subcontractor payments are approved in the accounts system, and the RCT notifications are handled manually by the bookkeeper or accountant via ROS. The connection between a specific job, the subcontractor invoice, the payment notification, and the deduction is maintained — if it is maintained at all — in a separate log.
This approach fails in predictable ways. A payment is made before the payment notification is submitted to Revenue — creating a technical breach even if the correct deduction is eventually withheld. A contract notification is missed for a new subcontractor because the person responsible did not know the subcontractor had been engaged until the invoice arrived. A deduction is applied at the wrong rate because the rate changed and nobody updated the records.
Each of these failures creates Revenue exposure. The exposure is not always caught immediately — Revenue audits can cover multiple years — but when it is caught, the liability is retrospective.
How RCT compliance works inside a connected operational system
In MaintenanceServiceOS and SupplyInstallOS as configured by Inovada, RCT compliance is built into the purchasing workflow rather than managed as a separate process.
When a purchase order is raised for a subcontractor, the system checks whether the subcontractor is registered in the RCT module. If they are, their deduction rate and contract notification status are displayed. If a contract notification has not been submitted for this subcontractor on this project, the system flags it before the PO is approved. The RCT deduction is calculated automatically when the invoice is matched to the PO, and the net payment amount is generated without manual calculation.
The payment notification workflow prompts the user to submit the notification to Revenue before releasing the payment. Monthly RCT return data is compiled from the system records rather than assembled manually from a log.
Common RCT mistakes Irish contractors make
Beyond the process failures described above, a few specific mistakes come up repeatedly in Irish trade businesses:
- Treating labour-only subcontractors as employees for payroll. If the relationship meets the criteria for a subcontract under the RCT rules, it should be handled through RCT — not PAYE. Getting this wrong creates both RCT and PAYE exposure.
- Applying the wrong deduction rate. Subcontractor rates change based on their Revenue compliance record. A rate that was 20% six months ago may now be 35%. The rate must be checked at the time of each payment notification — not assumed to be the same as last time.
- Missing the contract notification for ad-hoc subcontractors. One-off subcontractors engaged for a single job are still subject to RCT. The contract notification requirement applies regardless of contract value.
If your subcontractor management currently lives outside your job management system — in a separate spreadsheet or handled manually by your bookkeeper — the risk of a process failure is higher than it needs to be. RCT compliance should be embedded in the workflow that creates the purchase order, not managed as an afterthought when the invoice arrives.
To see how MaintenanceServiceOS handles RCT compliance in practice, book a discovery call.