Common RCT Mistakes Small Contractors Make And How To Avoid Them

This article breaks down the most common RCT mistakes small contractors make, why they happen, and what you can do to avoid them without turning your evenings into paperwork marathons.

Relevant Contracts Tax catches out small contractors more than any other tax rule in Ireland. Not because it is impossible to understand, but because it sits quietly in the background until something goes wrong. Then it gets loud, fast.

Most mistakes are not deliberate. They usually come from assumptions, rushed admin, or copying what someone else does on site. The problem is that Revenue does not care why a mistake happened. They care that it did.

This article breaks down the most common RCT mistakes small contractors make, why they happen, and what you can do to avoid them without turning your evenings into paperwork marathons.

Assuming RCT Only Applies To Big Jobs

This is probably the most damaging belief of all.

Many small contractors think RCT is only for large developments, housing estates, or major commercial builds. In reality, size does not matter. One subcontractor. One short job. One invoice. RCT can still apply.

If you are a principal contractor and you engage someone else to carry out relevant work, RCT may be triggered regardless of value or duration.

How to avoid it
Forget about job size. Focus on role. If you are paying another party for relevant operations, always stop and ask, does RCT apply here?

Paying A Subcontractor Before Sending A Payment Notification

This mistake happens all the time, especially on busy sites.

A subcontractor finishes a job, needs paying quickly, and you transfer the money with the intention of sorting RCT later. Unfortunately, Revenue does not allow later.

Under RCT rules, you must submit a payment notification before payment is made. Not after. Not the same day. Before.

How to avoid it
Build a simple habit. No payment leaves your account until a deduction authorisation is received. Treat it like a safety check, not an optional step.

Thinking A Verbal Agreement Is Not A Contract

Some contractors believe that if there is no written contract, RCT does not apply. This is false.

A contract for RCT purposes does not need to be written. A verbal agreement is still a contract. Even an ongoing arrangement without paperwork can qualify.

Revenue looks at what actually happened, not what was written down.

How to avoid it
Assume any agreement involving payment for relevant work is a contract unless proven otherwise. Register it properly and protect yourself.

Using The Wrong Subcontractor Details

This one feels minor, but it causes major headaches.

Incorrect tax numbers, business names that do not match Revenue records, or using a personal PPS number instead of a company tax reference can all cause rejected notifications or incorrect RCT rates.

Sometimes the subcontractor gives outdated details. Sometimes the contractor never checks them.

How to avoid it
Always verify subcontractor details before registering a contract. If something looks off, pause and confirm. Five minutes now can save months later.

Not Understanding RCT Rates

Another common mistake is assuming everyone is taxed at the same RCT rate.

In reality, Revenue assigns RCT rates based on the subcontractor’s tax compliance. These rates can change, sometimes without warning.

Paying the wrong amount because you assumed the rate stayed the same is still a mistake.

How to avoid it
Never rely on old rates. Always wait for the deduction authorisation issued through the system. That document is your instruction, not a suggestion.

Forgetting To Register The Contract At All

This often happens with repeat subcontractors.

You might have worked with the same person for years and assume the contract is already covered. But if the job is new, the site is new, or the scope has changed, a new contract may need to be registered.

Revenue tracks contracts individually, not relationships.

How to avoid it
Ask yourself a simple question for every new job. Is this a new contract? If yes, register it. Even if it feels repetitive.

Confusing Employees With Subcontractors

Small contractors sometimes blur the line between employees and subcontractors, especially when work is casual or short term.

RCT applies to subcontractors, not employees. If someone should be on payroll but is treated as a subcontractor, you can end up with problems beyond RCT, including PAYE issues.

How to avoid it
Do not decide based on convenience. Decide based on the reality of the working arrangement. Control, hours, tools, and risk all matter.

Ignoring ROS Messages And Notifications

The Revenue Online Service is not just a filing tool. It is how Revenue communicates with you.

Rate changes, reminders, and important notices are often delivered through ROS. Many small contractors log in only when they need to file something and miss key messages.

How to avoid it
Check ROS regularly, even when nothing is due. Treat it like email from Revenue, because that is essentially what it is.

Leaving RCT Until The End Of The Month

Some contractors batch everything at month end. That works for some taxes. RCT does not like batching.

Because notifications must be made before payment, leaving RCT admin until later almost guarantees mistakes.

How to avoid it
Handle RCT as you go. Register contracts when work starts. Submit notifications when payment is planned. Keep it live, not retrospective.

Assuming Your Accountant Will Automatically Handle Everything

This is a risky assumption.

Some accountants manage RCT fully. Others only advise. If roles are not clear, tasks get missed. Revenue will not accept “I thought my accountant did it” as an excuse.

How to avoid it
Clarify responsibility. Who registers contracts? Who submits payment notifications? Who monitors rates? Write it down if needed.

Poor Record Keeping

RCT records are not optional. Revenue can ask for them, sometimes years later.

Missing deduction authorisations, incomplete contract details, or no proof of notifications makes it difficult to defend your position during a review.

How to avoid it
Keep digital copies of everything. Contracts, notifications, authorisations, and payment records should all be easy to retrieve.

Fixing Mistakes Too Late

Many contractors know something is wrong but hope it will go unnoticed. That rarely works.

Revenue systems are automated and cross check data constantly. Problems usually surface eventually, and the longer they sit, the worse they get.

How to avoid it
If you spot an error, act immediately. Correcting mistakes early is almost always easier and cheaper.

Final Thoughts

RCT mistakes are rarely about lack of intelligence. They are about habits, assumptions, and timing.

Small contractors juggle quoting, tools, staff, suppliers, and cash flow. RCT admin can feel like an annoyance. But ignoring it is like ignoring a warning light on a van. It does not go away on its own.

Get the basics right, slow down around payments, and treat RCT as part of the job, not an afterthought. That mindset alone avoids most of the problems contractors run into.