How to Read an EV Charger Tariff Before You Plug In

By Tappy · April 26, 2026 · 6 min read

You've found a charger with a free bay. You plug in, and an hour later you check the app — and the total is €4 higher than you expected. Where did the extra come from? Almost certainly from a tariff line you didn't know to look for. EV charger pricing has more components than it appears, and most chargers don't make it easy to understand all of them before you start.

This guide breaks down every element you'll find on an EV charging tariff, what it actually means, and how to use that information to calculate your real cost before you commit.

The four main tariff components

1. Start fee (session fee / connection fee)

A flat charge applied once when you initiate a session, regardless of how much energy you use or how long you stay. Think of it as the charger's "cover charge" for opening the session on the network. Start fees vary widely: some operators charge nothing, others charge up to €1.50 per session.

Start fees can have a disproportionate effect on short, low-energy top-ups. If you're adding just 5 kWh at €0.39/kWh (€1.95 in energy), a €0.49 start fee adds 25% to your bill before you've drawn a single watt.

2. Energy fee (€/kWh)

The cost per kilowatt-hour of electricity drawn. This is usually the largest component for any reasonably long session. It's what the charge point operator pays for the electricity, plus their margin. It varies by operator, location, and sometimes by time of day (peak vs off-peak).

Note: if you're using a charging app like Tappy, your plan may add a small surcharge on top of the operator's energy fee. On Tappy Flex this is €0.024/kWh; on Comfort it's €0. This should always be disclosed separately — and Tappy shows it as a distinct line item.

3. Time fee (€/min or €/hour)

Some chargers — particularly fast DC chargers — charge per minute of connection time instead of, or in addition to, per kWh. This is more common on rapid chargers where the operator wants to maximise throughput. A time fee punishes slow chargers (older vehicles, low state of charge at arrival) disproportionately. Always check whether the tariff is energy-based, time-based, or both.

4. Idle fee (overstay fee)

An idle fee kicks in when your car remains plugged in after charging is complete — or after a defined session time limit — and you haven't moved. The charger starts billing per minute to encourage you to free up the bay. This is the fee that most commonly surprises drivers, because it can equal or exceed the cost of the actual charging if you're away long enough.

Idle fees have two parameters you need to know: the threshold (how long after charging completes before the fee starts — often a 15–60 minute grace period) and the rate (typically €0.05–€0.20/min in the EU).

We cover this in detail in our dedicated guide: What is an EV charger idle fee?

A real tariff, decoded

Here's what a Tappy tariff screen looks like for a typical public AC charger:

If you charge 22 kWh and unplug within the 60-minute idle threshold:

If you leave the car for 45 minutes after charging completes (past the 60-min threshold — so 45 - 0 grace minutes at €0.10/min):

The 45 extra minutes added €4.50 — nearly 50% more than the session itself. That's not unusual.

Why tariffs are so confusing in practice

EV charging pricing is more fragmented than almost any other utility. Here's why it's hard:

• No standard format. There's no regulation requiring operators to display tariffs in a consistent way. Some show just the kWh rate; others show only a per-minute rate; very few show the idle fee upfront.
• Screen real estate is limited. Charger displays are often small, low-contrast, and cluttered. Critical information like idle thresholds can be buried in a second screen you're not prompted to view.
• Roaming adds a layer. If you're charging on a network other than your home network (roaming), your eMSP (the app or card you used to start) adds a margin on top of the CPO's base tariff. This margin is often not shown at the charger — it only appears on your final invoice.
• Time-of-day pricing. Some operators have peak and off-peak rates. The price displayed when you walk up may not be the price you pay if you plugged in at peak time and are finishing at off-peak (or vice versa).
• VAT varies. Tariffs are sometimes displayed ex-VAT, sometimes incl. VAT. In the EU, electricity for EV charging is typically subject to the standard VAT rate (21% in the Netherlands, for example), which can make a meaningful difference.

What to check before every session

1. Start fee — flat cost regardless of energy used. Watch out for high start fees if you're doing a short top-up.
2. kWh rate — your main cost driver for longer sessions. Compare to your home electricity rate as a mental benchmark.
3. Time fee — if present, calculate the worst-case total based on how long you expect to charge.
4. Idle fee threshold — the grace period after charging completes. Plan your return time around this number.
5. Idle fee rate — how much per minute if you exceed the threshold.
6. Roaming margin — if you're charging on a different network via an app or card, check whether your provider discloses the full price including their margin.

The formula for estimating your session cost

Total = Start fee + (kWh charged × €/kWh rate) + (idle minutes × idle rate)

For a practical estimate: look up your car's AC charging rate (e.g., 11 kW), decide how long you'll charge (e.g., 1.5 hours), and multiply: 11 × 1.5 = 16.5 kWh. Then apply the tariff components above.