Learn Italian: Il visto va controllato dal funzionario. - The visa must be checked by the official.

This is the passive of necessity. When you use a simple tense of andare (like the present tense va) followed by a past participle (controllato), it means an action must or needs to be done. So, va controllato means "must be checked" or "needs to be checked."

Could I say deve essere controllato instead?

Yes! Il visto deve essere controllato... means the exact same thing. However, using andare to express obligation in the passive voice is extremely common in spoken and written Italian, especially for rules, instructions, or chores.

Does the ending of controllato change depending on the subject?

Yes, it must agree with the subject in gender and number. Because il visto (the visa) is masculine singular, the participle is controllato. If the subject were feminine, like la valigia (the suitcase), it would be la valigia va controllata.

Why use dal instead of da for "by"?

In passive sentences, the person or thing doing the action is introduced by the preposition da (by). Since the sentence refers to "the official" (il funzionario), you have to combine da with the definite article il to create the combined word dal.