If you have to say there’s something you have to do or that has to be done, here’s how you can do it in Spanish.

Tener Que

Perhaps the most common way of saying “to have to” in Spanish istener que followed by an infinitive.

• Tengo que pagar impuestos. (I have to pay taxes.)
• Mi padre tiene que ir a Barranquilla. (My father has to go to Barranquilla.)

Tener que is the phrase for “statements of necessity” that is usually learned first by students of Spanish because it is very common and doesn’t require the knowledge of any verb conjugation beyond the forms of tener.

But there are other ways as well to make statements of necessity.

Hay Que

Another that is even easier to learn because it doesn’t require any conjugation is hay que, again followed by an infinitive:

• Hay que ser muy listo. (It is necessary to be very ready.)
• ¿Por qué hay que usar códigos? (Why is it necessary to use codes?)

Necesitar Que and Es Necesario Que

As might be expected, some other phrases used in statements of necessity are closely related to the word “necessary.” One is the impersonal verb necesitar, meaning “to be necessary,” which can be followed by que and a verb in the subjunctive mood.

• Necesito que un experto me contacte. (I need an expert to contact me. A word-for-word translation would be: I need that an expert contact me. Many of the other translations below where the subjunctive is used follow a similar pattern.)
• Necesitas que alguien te escuche. (You need someone to listen to you.)

Similarly, it is possible to use the impersonal phrase es necesario que, which also is followed by a verb in the subjunctive.

• Es necesario que Europa conserve su herencia. (It is necessary for Europe to retain its heritage.)
• Es necesario que nos envíen los datos. (It is necessary for them to send us the data.)

Two Es Phrases

Less common than the above is the impersonal phrase es preciso, which also means “it is necessary.” It is usually followed by an infinitive, but it also can be followed by que and a subjunctive verb.

• Es preciso revisar el diseño y la organización del programa. (It is necessary to change the design and organization of the program.)
• Es preciso que trabajen. (It is necessary for them to work.)

The impersonal phrase es importante, meaning “it is important,” is used in the same way, although it isn’t as forceful as es necesario.

• Es importante saber sobre interoperabilidad. (It is important to know about interoperability.)
• Es importante que el sitio web esté en español. (It is important that the website be in Spanish.)

Urgir

Finally, to indicate that something is urgently necessary, it is possible to use the impersonal phrase urge que from the verb urgir, again followed by a verb in the subjunctive.

• Urge que X’cacel sea declarada como reserva natural protegida. (It is urgent that X’cacel be declared a natural protected reserve.)
• Me urge que todo el mundo lo lea. (It is urgent to me that everybody read it.)

The verb urgir can also stand alone as a verb to mean “to be urgently needed.”

• Urge atención inmediata el caso de los asesinatos de mujeres en Ciudad Juárez. The case of women murdered in Cuidad Juarez urgently needs attention.)
• Me urge ayuda sobre los siguientes terminales. (I urgently need help with the following terms.)

Read more at: http://spanish.about.com/od/sentencestructure/a/necessity.htm