La facture rectificative réduit l’impayé.

In French, most descriptive adjectives come after the noun.
So facture rectificative is the normal order: noun + adjective.

• une facture rectificative = a corrective/amended invoice

Some adjectives do come before the noun, but rectificatif / rectificative is not one of them.

Because it agrees with facture, which is a feminine noun.

• un document rectificatif
• une facture rectificative

French adjectives usually change form to match the noun in gender and number.

It is the definite article le or la shortened before a vowel sound. This is called elision.

Here:

• le impayé ❌
• l’impayé ✅

So l’ stands for the article before impayé.

Réduit is the present tense form of the verb réduire for a third-person singular subject.

Conjugation:

• je réduis
• tu réduis
• il/elle/on réduit

Since the subject is la facture rectificative (singular), the verb must be réduit.

The é is part of the spelling of the verb réduire and its forms.

• infinitive: réduire
• present: il/elle réduit

This accent affects pronunciation and is not optional. French spelling often preserves these accents across related forms.

Here impayé is being used as a noun, not just an adjective.

As an adjective, impayé means unpaid.
As a noun, it can mean something like:

• an unpaid amount
• an outstanding debt
• a non-payment / overdue balance

So in this sentence, l’impayé refers to the unpaid amount or outstanding balance.

Because the sentence is talking about one unpaid amount / one outstanding balance as a single thing.

If it referred to multiple unpaid items, you might see:

• les impayés = unpaid amounts / arrears / bad debts

Here it is treated as one overall amount, so singular l’impayé is natural.

Yes, French can use other expressions depending on context. For example:

• facture rectificative
• facture corrigée
• facture de correction
• avoir (in some accounting contexts, if it is a credit note rather than simply a corrected invoice)

Facture rectificative is formal and common in administrative, tax, or accounting language.

French does not use do/does as an auxiliary in ordinary present-tense statements the way English does.

English:

• The corrected invoice reduces the unpaid amount.

French simply uses the main verb:

• La facture rectificative réduit l’impayé.

So there is no separate word corresponding to English does here.

The subject is the noun phrase before the verb:

• La facture rectificative = subject
• réduit = verb
• l’impayé = direct object

So the structure is:

[subject] + [verb] + [object]

This is the standard French word order in a simple statement.

A careful pronunciation would be approximately:

la fak-tyr rek-ti-fi-ka-tiv ray-dwee lam-pay-yay

A few useful points:

• facture: the u is a French u sound, not like English oo
• rectificative: the final -ve is pronounced
• réduit: sounds like ray-dwee
• l’impayé: the l’ links directly into the next word

In natural speech, French flows smoothly from one word to the next.

Yes, depending on the exact meaning.

• la dette = the debt
• le montant impayé = the unpaid amount
• l’impayé = the outstanding/unpaid balance, often in accounting or business language

So l’impayé is slightly more technical or administrative in tone. In many contexts, le montant impayé may sound clearer to learners.