Common Revenue Audit Triggers for Travel & Subsistence Expenses
Revenue doesn't audit randomly. They use risk-based profiling — certain patterns in your payroll submissions, ERR filings, and tax returns flag businesses for closer examination. Travel and subsistence is a specific focus area because T&S payments are tax-free and easy to abuse.
An audit isn't just about penalties. It's about the retrospective loss of tax-free treatment — which can turn a €30,000 annual T&S bill into a €48,000+ tax liability.
The 8 Most Common T&S Audit Triggers
Missing or late ERR filings
Revenue uses ERR data for real-time risk profiling. If your competitors in the same industry are filing ERR regularly and you're not, you're already flagged. Missing filings signal that your T&S process may be non-compliant in other ways too. See ERR deadlines.
Inconsistent mileage rates across employees
If Employee A claims at €0.5182/km and Employee B claims at €0.9063/km for similar trips, Revenue will ask why. The answer should be "different band positions" — but if you can't demonstrate cumulative tracking, it looks like arbitrary rates. This is the #1 sign of spreadsheet-based management.
No mileage logs or incomplete logs
Revenue requires 6 mandatory fields: date, origin, destination, distance, business purpose, vehicle registration. Missing any one can result in the entire claim being disallowed. The most commonly missing: business purpose and vehicle reg. See mileage log template.
Claiming mileage for commuting
Revenue's single most common disallowance. Home to your normal place of work is commuting — always, even if it's 100 km. The risk increases with remote and hybrid workers who may claim their "office day" commute as business travel.
Flat-rate mileage instead of progressive bands
If Revenue sees every mileage claim for the year uses the same per-km rate, they know progressive bands aren't being applied. A flat rate is never correct for an employee doing more than 1,500 km/year. This is the clearest indicator of manual processing without proper band tracking.
Subsistence claims without time records
Subsistence is based on duration away. If claims don't include departure and return times, Revenue can't verify the rate is correct. Claiming the 10+ hour rate (€46.17) for a trip that lasted 6 hours triggers deeper review.
Excessive mileage relative to the role
Revenue benchmarks claims against industry norms. A desk-based office worker claiming 20,000 km/year looks unusual. A sales rep claiming the same is normal. If totals seem high relative to job functions, Revenue may request individual journey breakdowns.
Mixing "country money" with civil service rates
Specific to construction: paying some workers under the €181.60/week site-based scheme and others under civil service mileage rates — or accidentally paying both to the same worker. Revenue specifically targets this inconsistency.
What Happens During a T&S Audit
Revenue will request:
Where problems are found: Revenue compares what you paid (payroll) against what you reported (ERR) against your supporting records (mileage logs). Discrepancies between these three data sources are where audits find issues.
What Are the Consequences
Loss of tax-free treatment
Revenue can retrospectively treat all T&S payments as taxable income. Employer owes employer PRSI (11.05%). Employee owes PAYE (up to 40%) and USC (up to 8%). On €30,000 of annual T&S payments, the total additional liability can exceed €17,000.
Interest
Revenue charges daily interest on underpaid tax — currently 0.0219% per day (approximately 8% per year). This accumulates from the original due date, not the audit date.
Penalties
Up to 100% of the underpaid tax in cases of deliberate non-compliance. Even careless errors attract penalties. Voluntary disclosure before Revenue contacts you reduces penalties to 3-5%.
Publication
In severe cases, Revenue publishes names on the quarterly tax defaulters list. Rare for T&S issues but possible for large-scale deliberate non-compliance.
How to Audit-Proof Your T&S Expenses
Frequently Asked Questions
Compliance Resources
Audit-Ready Records, Automatically
Expense.ie generates everything Revenue would request in an audit — progressive band rates, complete mileage logs, timestamped subsistence, ERR exports, and full approval history. No manual compilation. No gaps.
30-day money-back guarantee. No long contracts.