Comparamos la declaración conjunta y la declaración individual.

Comparamos is the 1st person plural form of comparar (to compare), so it means we compare or we are comparing, depending on context.

A useful extra point: comparamos can also mean we compared in the preterite. In isolation, the form is ambiguous. Context normally tells you whether it is present or past.

Spanish often omits subject pronouns because the verb ending already shows who is doing the action.

• Comparamos = we compare / we compared

So nosotros is not necessary. You could say Nosotros comparamos..., but that usually adds emphasis, contrast, or clarity.

For example:

• Nosotros comparamos la declaración conjunta, no ellos.
  = We compare the joint return, not them.

Because Spanish commonly repeats the article when mentioning two separate noun phrases joined by y.

So:

• la declaración conjunta
• la declaración individual

This makes both items sound complete and balanced. It is the most natural wording here.

If you left out the second la, the sentence would sound less standard in this structure.

Because the word that comes immediately after the conjunction is la, not individual.

Spanish changes y to e before a word beginning with an i- or hi- sound:

• padres e hijos

But here the sequence is:

• y la declaración individual

Since la does not begin with an i sound, y stays y.

In Spanish, adjectives often come after the noun, especially when they classify or identify a type.

So:

• declaración conjunta = joint declaration/return
• declaración individual = individual declaration/return

This is very normal Spanish word order. Putting these adjectives before the noun would sound unnatural here.

Because declaración is a feminine singular noun, and conjunta must agree with it.

• la declaración → feminine singular
• conjunta → feminine singular adjective

Compare:

• el documento conjunto
• la declaración conjunta

Because individual is an adjective with the same form for masculine and feminine singular.

So you get:

• el trámite individual
• la declaración individual

Only the article and noun show the gender clearly here. In the plural, it becomes:

• individuales

It has an accent because the stress falls on the last syllable:

• de-cla-ra-ción

Without the accent, Spanish spelling rules would make you stress it differently.

A helpful pattern: many nouns ending in -ción have a written accent:

• nación
• información
• declaración

A rough Spain pronunciation is:

comparamos la declaración conjunta y la declaración individual

Approximate English-style guide:

kohm-pah-RAH-mohs la deh-klah-rah-THYON kohn-HOON-tah ee la deh-klah-rah-THYON een-dee-bee-DWAL

A few key sounds in Spain Spanish:

• c before i in declaración = th sound, like in thin
• j in conjunta = a strong throaty sound
• y here sounds like ee

Yes. That is also correct, and in many contexts it can sound even more explicitly like we compare one with the other.

Compare:

• Comparamos la declaración conjunta y la declaración individual.
• Comparamos la declaración conjunta con la declaración individual.

Both are correct. The version with con makes the contrast a bit more explicit.

Yes, if the context is clear.

For example:

• Comparamos la declaración conjunta y la individual.

This is very natural, because the second phrase clearly refers back to declaración.

You can even hear:

• la conjunta / la individual

in contexts where everyone already knows you are talking about tax returns or declarations, but that is more context-dependent.

Yes, very often.

In Spain, declaración conjunta and declaración individual are commonly used when talking about tax returns, especially whether people file jointly or individually.

So even if the sentence could be understood more generally, many native speakers would naturally think of a tax return context.