En el formulario hay que escribir el nombre completo y el domicilio.

Hay que + infinitive is a very common Spanish structure meaning it is necessary to..., you have to..., or one must....

So hay que escribir means you have to write / it is necessary to write.

Why not just escribir? Because escribir alone only means to write. It does not express obligation.

A few comparisons:

• Escribir el nombre = to write the name
• Hay que escribir el nombre = you have to write the name

This structure is impersonal, so it does not say who specifically must do it. It is often used in instructions, rules, and notices.

Both can express obligation, but they work differently.

• Hay que + infinitive = general, impersonal obligation

  • Hay que escribir el nombre completo.
  • One must / You have to write the full name.

• Tener que + infinitive = a specific person has to do something

  • Tengo que escribir mi nombre completo.
  • I have to write my full name.

In a form instruction, Spanish often prefers hay que because the instruction is general rather than addressed to one named person.

Because in Spanish, formulario here needs the definite article: el formulario = the form.

So:

• en el formulario = on/in the form

Spanish uses articles more often than English does. English may say on the form, and Spanish matches that with en el formulario.

Also, en can mean both in and on, depending on context. With forms, documents, pages, and spaces where information is written, en is the normal preposition.

In this context, it is best understood as on the form.

Spanish uses en for both ideas in many cases, so the exact English translation depends on context.

Examples:

• en el formulario = on the form
• en la mesa = on the table
• en la caja = in the box

So the Spanish preposition stays the same, but English may choose in or on.

Spanish often uses the definite article where English might omit it.

So:

• el nombre completo = the full name
• el domicilio = the address

In instructions and formal language, articles are very common:

• Hay que firmar el documento.
• Hay que escribir el apellido.

Leaving out the article here would sound less natural.

Nombre completo means full name.

In practice, that means all the name information the form expects. In Spain and much of the Spanish-speaking world, this often includes:

• given name(s)
• first surname
• second surname, if applicable

So it can be broader than what an English speaker might casually think of as just first name + last name.

Domicilio means address, especially home address or official address.

It is similar to dirección, but there is a difference in tone:

• dirección = the usual everyday word for address
• domicilio = more formal, often used in legal, official, or administrative contexts

Since this sentence is about a form, domicilio sounds very natural.

Because this sounds like formal or administrative Spanish.

On forms and in official documents, Spanish often uses more formal vocabulary such as:

• domicilio
• apellidos
• fecha de nacimiento
• documento de identidad

In everyday conversation, someone is more likely to ask:

• ¿Cuál es tu dirección?

But on an official form, domicilio is very common and appropriate.

In Spanish, most adjectives normally come after the noun.

So:

• nombre completo = full name
• casa grande = big house

This is the normal word order. Some adjectives can go before the noun, but that often changes the tone or meaning. Here, nombre completo is simply the standard expression.

Because completo agrees with nombre, and nombre is a masculine singular noun.

So:

• el nombre completo
• la dirección completa

The adjective must match the noun in gender and number:

• masculine singular: completo
• feminine singular: completa
• masculine plural: completos
• feminine plural: completas

Because hay que is impersonal. It does not need a subject.

The sentence is not saying:

• you write
• he writes
• they write

It is saying:

• it is necessary to write
• you have to write in a general sense

This is very common in instructions because it sounds neutral and general.

Yes, it sounds neutral-to-formal, mainly because of:

• hay que for impersonal instructions
• formulario
• domicilio, which is formal vocabulary

It sounds exactly like the kind of sentence you would see in paperwork, administration, or official instructions.

Yes, that is possible, but it means something slightly different in feel.

• Hay que escribir... = you have to write... / it is necessary to write...
• Se escribe... = ...is written / you write... in a general instructional sense

Both can appear in instructions, but hay que escribir is more directly about obligation.

So:

• En el formulario hay que escribir... = clearer as an instruction
• En el formulario se escribe... = more like explaining what one writes on the form

Because y means and, joining the two things that must be written:

• el nombre completo
• el domicilio

So the structure is:

• hay que escribir
  • item 1 + y
    • item 2

In Spanish, y changes to e before words beginning with an i sound, but not here, because domicilio begins with d.

Yes, in some contexts Spanish speakers do say poner for filling in forms:

• Hay que poner el nombre completo y el domicilio.

That can sound natural in everyday speech. However:

• escribir = more literally to write
• poner = often used in the sense of to put / fill in / enter

In a formal instruction, escribir is very clear and completely natural.

Not exactly.

• formulario = form
• impreso = printed form or document, often more old-fashioned or formal

In modern general use, formulario is the more straightforward word for a form you complete.

So this sentence sounds normal and current:

• En el formulario hay que escribir...

A more everyday version might be:

• En el formulario tienes que escribir tu nombre completo y tu dirección.

Differences:

• tienes que addresses you directly
• tu dirección is less formal than el domicilio

But the original sentence is better if the goal is neutral official instructions.