La pérdida patrimonial reduce la base imponible.

Because both nouns are feminine singular:

• la pérdida = the loss
• la base imponible = the taxable base / tax base

In Spanish, articles must agree with the noun in gender and number. Here:

• pérdida is feminine singular
• base is also feminine singular

So both take la.

This is a fairly formal, financial/tax expression. It refers to a capital loss or loss of assets/wealth, depending on context.

A useful breakdown:

• pérdida = loss
• patrimonial = relating to assets, wealth, estate, or patrimony

In Spanish tax language, ganancia patrimonial and pérdida patrimonial are common fixed terms.

Because patrimonial is an adjective, while patrimonio is a noun.

• patrimonio = assets, estate, patrimony, wealth
• patrimonial = relating to those assets or that estate

So:

• pérdida patrimonio would be incorrect
• pérdida patrimonial is correct because the adjective modifies pérdida

It works like:

• financial loss
• capital loss
• asset-related loss

Because in Spanish, adjectives often come after the noun, especially in formal or technical language.

So:

• pérdida patrimonial = patrimonial loss / capital loss
• base imponible = taxable base

This is much more natural in Spanish than putting the adjective first.

Reduce is the third-person singular present indicative of reducir.

Conjugation of reducir in the present:

• yo reduzco
• tú reduces
• él/ella/usted reduce
• nosotros reducimos
• vosotros reducís
• ellos/ellas/ustedes reducen

In the sentence, the subject is La pérdida patrimonial, which is singular, so the verb must be reduce.

Because the subject is singular.

The subject is:

• La pérdida patrimonial = one loss / the capital loss

So the verb must be singular too:

• La pérdida patrimonial reduce...

If the subject were plural, then you would use reducen:

• Las pérdidas patrimoniales reducen la base imponible.

Spanish normally does not use an English-style possessive structure like the company’s losses inside expressions like this. Instead, it often uses:

• an adjective, as in patrimonial
• or a de phrase, such as la pérdida de patrimonio

So Spanish tends to build these ideas differently from English.

Yes. Base imponible is a standard tax/legal term in Spanish.

It refers to the amount on which a tax is calculated before the final tax due is determined. In everyday learning terms, it is best treated as a set phrase.

A few useful related terms:

• base imponible = taxable base / tax base
• tipo impositivo = tax rate
• cuota tributaria = tax amount due

So even if imponible looks unusual, the full phrase is very common in tax contexts.

Imponible is an adjective meaning something like taxable or subject to taxation in this context.

It comes from imponer, but in tax language you should usually learn it as part of the phrase:

• base imponible

That is more useful than trying to translate imponible in isolation every time.

The accent mark shows the stress: PÉR-di-da.

Without going too deep into spelling rules, Spanish uses accent marks when a word’s stress does not follow the default pattern. In pérdida, the written accent tells you the stress falls on the first syllable.

This also helps distinguish correct pronunciation.

Not in normal standard Spanish.

In a complete sentence like this, Spanish usually needs the articles:

• La pérdida patrimonial reduce la base imponible.

Dropping the articles would sound unnatural and incomplete, except perhaps in note-taking, headlines, tables, or very abbreviated technical writing.

Not really in casual conversation. It sounds formal, technical, and specifically related to tax, accounting, or legal/financial language.

A native speaker would expect to see it in places like:

• tax documents
• accounting explanations
• legal or financial reports
• administrative forms or guidance

So it is perfectly natural Spanish, but in a specialist register.

Yes, depending on context. Spanish reducir is often translated as:

• reduce
• decrease
• lower

In this sentence, all of these are close in meaning. In tax or accounting English, reduces is usually the safest and most neutral choice.