There is no fixed number of classes that you must specify in a trade mark application. The right choice depends on the products and services for which you now use your name or logo, and for which you will reasonably do so in the foreseeable future. If you choose too few classes, your mark will not be protected outside those classes and another party can register the same name there. If you choose too many, you pay unnecessary fees for protection you may never use, and that can even work against you later.
This last point is the detail most often overlooked in this question. A trade mark registration does not automatically protect everything on the application form: if a mark in a particular class is not actually used over time, a third party can request that the mark be revoked for that class. Selecting classes "just to be safe" therefore not only incurs extra costs, but also creates a register entry that will prove less solid in a dispute than it appears.
What the Nice Classification covers
Both the BOIP and EUIPO use the same international classification system, the Nice Classification: 45 classes, the first thirty-four covering products and the last eleven covering services. Each class has its own description and a list of terms that fall under it. A trade mark application is always filed for one or more of those classes, never in a general sense for "everything". Two businesses can use the same name as long as they operate in different classes and there is no likelihood of confusion between what they offer.
The class structure is updated from time to time, with new terms for products and services that did not exist before. This particularly affects businesses operating in rapidly changing sectors, such as software and digital services.
Too few classes: the most direct damage
The most common scenario is that a business limits itself to the class that seems most obvious at the time of application, leaving the rest of its business activities unprotected. An installation company that also sells maintenance contracts and advice alongside installation work naturally falls into multiple classes at once. If only the core activity is registered, a competitor can register the same name for the other activities and then use it against you.
The conflict scan that precedes an application shows exactly how things stand in practice for a specific name. get an indication without an account in advance provides an initial overview of what is already registered in the classes that appear relevant to you.
Too many classes: fees and a vulnerable register
On the other hand, there is the application that includes ten or fifteen classes for precaution, while the business actually uses two or three. The BOIP and EUIPO typically charge a basic fee for the first number of classes and a surcharge per class above that, so each additional class increases the fee paid directly to the office. That amount is separate from the service fee for the guidance itself; on the page with an overview of both cost items that distinction is set out separately.
More important than the cost is the effect over the longer term. Classes in which products or services under the mark are never actually offered provide protection on paper but lack substance. If you let a mark sit unused in a class, you risk a third party later successfully having that class removed. A mark is therefore strongest when the registered classes match what actually happens under that name.
How you reach a targeted choice
A useful starting point is the question: in which classes am I already offering products or services, and what expansion is realistic within a few years, not just conceivable? An installation company considering selling materials itself does well to include that class from the start. A service mentioned only as a passing thought during a meeting does not automatically belong.
Because the class system is technical and the consequences of a wrong choice become visible only years later, this step is not left to the applicant when filing. With guided filing, the class selection is aligned with the actual and foreseeable activities of the business before the application is prepared. More about how that process works can be found on the page where we determine which classes fit your situation.
What if your activities change later
A trademark registration fixes the classes at the time of filing; a class that becomes relevant later does not automatically fall under it. If your business expands to a new activity, that is the time to check whether additional filing is needed, not to wait until a conflict arises. Questions about such interim situations, and about when an expansion is or is not urgent, are worked out in the collection of practical questions about trademark registration.
For the exact class allocation of a specific product or service, the official Nice Classification and the harmonised TMclass list remain the source; if in doubt about the legal consequences of a class choice in a specific dispute, a trademark attorney is the right party to consult.
Would you like to know how your name appears in the existing registers, and in which classes that is relevant? The quick scan is free and gives you a first indication within a few minutes, without needing to create an account.