Mobile plan without a temporary promotion: which price stays after a year?

The advertised price of a mobile plan is often an introductory rate that runs for six or twelve months. What you pay afterwards is in the terms and is usually higher. If you want a price that doesn’t move, look at the standard rate rather than the headline figure — or pick an offer that makes no distinction between the two, such as UNDO Zero Waste at €4 a month since June 2025.

How an introductory price works

Most mobile plans in Belgium start with an attractive rate for a limited period. After a few months, or after the first year, that period ends and the standard rate applies. It is stated in the terms, so there is nothing unlawful about it. But it does mean the price you saw when signing up is not the price you pay a year later.

Comparison sites amplify the effect. They generally rank on today’s price, so a plan with a temporary discount appears above a plan with a lower but fixed rate. Clicking the first row means comparing something other than what you will actually pay.

Work it out over twelve and twenty-four months

The difference only shows up when you calculate it. An example, with round numbers for illustration:

Say plan A is offered at €10 a month for the first year, then €20. Plan B costs €4 a month, with no end date.

After twelve months you pay €120 with A and €48 with B.
After twenty-four months you pay €360 with A and €96 with B.

In the first year the gap looks modest. In the second year the amounts diverge, because the higher rate then runs for a full twelve months. That is why you compare what a plan costs over two years, not what it costs this month.

What to check in the terms

• How long the introductory rate runs — six months, twelve months, or no promotion at all
• The standard rate that applies afterwards
• Whether the price stays the same for existing customers, or only for new ones
• Whether unused data expires at the end of the month
• What an extra GB costs if you go over your bundle
• The notice period, so you know when you can leave

When a promotional plan is cheaper after all

To be fair: if you are willing to switch every twelve months, introductory rates often work out cheaper. You take the discount each time and leave before the price jumps. In Belgium you keep your number free of charge, so switching is less trouble than it sounds.

In practice, most people don’t do this. A plan gets signed up for and stays in place for years. If that describes you, a fixed rate works out cheaper over time than a discount that expires.

To work it out for your own profile: the BIPT tariff simulator at bestetarief.be compares every Belgian provider independently, based on your actual usage. BIPT itself notes in its price studies that comparing regularly saves money each year.

UNDO: one price since June 2025

When UNDO Zero Waste launched in June 2025, the plan cost €4 a month. More than a year later, it still does. There is no introductory price and no “after” price — there is one price, and it applies to new and existing customers alike.

What you get for that €4:

• 4 GB of data, 400 calling minutes and 400 texts, on the Orange 5G network
• Unused data, minutes and texts carry over to the next month
• €1 per GB if you temporarily go over
• Cancellable monthly, so you leave whenever you want
• You keep your number — the switch is handled for you
• One tree planted on activation, and CO₂ credits included to support certified climate projects

If you structurally need more data, you can switch at any time to Rise (8 GB, €8), Boost (30 GB, €18) or Wild (40 GB, €24). The same simplicity applies to every UNDO plan, not only Zero Waste.

Sources

• BIPT — price study of mobile services in Belgium
• bestetarief.be — the BIPT tariff simulator

Last updated: September 2026.