La somme sur la facture est trop élevée.

In French, every noun has a grammatical gender that you simply have to learn with the word.
Somme (meaning “sum, amount of money”) is a feminine noun, so it always takes la (or une, de la, sa, etc.).

• la somme, une somme, cette somme
• not: le somme

There is no logical rule that makes somme feminine; it is just part of its dictionary form: (une) somme.

All three can relate to money, but they are used a bit differently:

• la somme: the sum/amount, often focused on the total (mathematical or financial).
  
  • La somme sur la facture est trop élevée. = The total amount on the invoice is too high.
• le montant: the amount, especially in financial/official contexts (bank forms, invoices, contracts).
  
  • Le montant de la facture est trop élevé.
• le prix: the price (of a product or service).
  
  • Le prix de ce repas est trop élevé.

In your sentence, you could also say Le montant de la facture est trop élevé, which is very natural and perhaps slightly more formal.

The preposition sur is very common with documents in French. It often means “on / in (the text of)”:

• sur la facture = on the invoice (as written on it)
• sur le contrat = in the contract
• sur la liste = on the list

You sometimes see de la facture with montant:
Le montant de la facture est trop élevé. = literally “the amount of the invoice is too high.”

But dans la facture would sound odd here; we normally talk about information sur (on) a document, not dans it.

Yes, you can say La somme est trop élevée if the context makes it obvious that you are talking about the invoice. That would sound natural in a conversation where the bill is already the topic.

However, La somme sur la facture est trop élevée is more precise, especially if there could be confusion (for example, if you might be comparing several amounts: on the invoice, on a quote, in your bank account, etc.).

Facture is a feminine noun: la facture, une facture. As with somme, this gender is arbitrary and must be memorised.

Meaning-wise, la facture usually means:

• a bill in a restaurant
• an invoice from a company or a service provider

In more formal business contexts, English might say invoice, and everyday speech might say bill, but French uses facture for both.

• très = very (high, big, nice…)
  
  • La somme est très élevée. = The amount is very high (neutral description).
• trop = too (excessively)
  
  • La somme est trop élevée. = The amount is too high (it should not be that high / it’s a problem).

So using trop élevée clearly expresses a complaint or judgement that the amount is higher than it should be. Très élevée just describes it as “very high” without necessarily saying it is unacceptable.

Élevé / élevée is an adjective meaning “high.” In French, adjectives usually agree in gender and number with the noun they describe:

• masculine singular: élevé
• feminine singular: élevée
• masculine plural: élevés
• feminine plural: élevées

Here, somme is feminine singular (la somme), so the adjective must match: élevée.

These three adjectives are not used in exactly the same way:

• élevé(e): “high” in the sense of a level, rate, or amount.
  
  • Un prix élevé, une somme élevée, un taux élevé.
• cher / chère: “expensive.”
  
  • Cette facture est très chère. = This bill is very expensive (the things you paid for cost a lot).
• haut / haute: “high” in a physical or vertical sense (height, position).
  
  • Une montagne haute, un mur haut.
    It is not normally used for the total on a bill.

So La somme sur la facture est trop élevée is the natural choice here; trop chère would focus more on the perceived expensiveness of what you bought, not the numeric total as such.

In French, most adjectives come after the noun:

• une somme élevée
• un prix raisonnable
• une maison ancienne

So la somme élevée is normal word order.
You cannot say l’élevée somme; that sounds wrong.

Only certain “short/common” adjectives (often remembered with BANGS or BAGS: Beauty, Age, Number, Goodness, Size) usually come before the noun: beau, vieux, trois, bon, grand, etc. Élevé does not belong to that group.

The sentence itself is grammatically fine but quite direct; it clearly says the amount is “too high,” which can sound like a complaint.

To be more polite or softer, you can phrase it differently, for example:

• Je trouve que la somme sur la facture est un peu élevée.
  (I find that the amount on the invoice is a bit high.)
• Le montant indiqué sur la facture me paraît élevé.
  (The amount shown on the invoice seems high to me.)
• Excusez-moi, le montant sur la facture me semble trop élevé.
  (Excuse me, the amount on the invoice seems too high to me.)

Adding je trouve, me semble, me paraît, or un peu softens the statement.

Yes.
Le montant de la facture est trop élevé. is very natural and, in many contexts, actually more common than La somme sur la facture est trop élevée.

Nuance:

• La somme sur la facture focuses on the sum written on it.
• Le montant de la facture focuses on the overall amount of the invoice.

Both are correct; montant de la facture is slightly more standard in business or formal contexts.

Approximate pronunciation (in IPA):

• La somme → /la sɔm/
• sur la facture → /syʁ la faktyʁ/
• est trop élevée → /ɛ tʁo elve/

Key points:

• The p in trop is silent here: trop → /tʁo/, not /tʁop/.
• There is no obligatory liaison between trop and élevée in normal speech; you usually say tʁo‿elve, with a slight glide, but not /tʁop‿elve/.
• facture → /faktyʁ/ (the final e is not pronounced; it just shows feminine gender in writing).