yatin wo harau mae ni, kouza no zandaka wo kakuninsimasita.

Because when 前に means before doing, the verb before it normally stays in the dictionary form.

• 払う前に = before paying
• 食べる前に = before eating
• 行く前に = before going

By contrast, 後で / 後に often uses the past form:

• 払った後で = after paying

So this is a very common pattern:

• Verb dictionary form + 前に
• Verb past form + 後で / 後に

Here, 前に means before in a time-sequence sense.

So:

• 家賃を払う前に = before paying the rent

It tells you that the action in the main clause happened first:

1. checked the account balance
2. then paid the rent

It does not mean a physical location like in front of here. Context makes it clearly temporal.

Because there are two different direct objects in two different actions.

• 家賃を払う = to pay rent
  • 家賃 is the thing being paid
• 残高を確認しました = checked the balance
  • 残高 is the thing being checked

So each verb has its own object:

• 払う takes 家賃を
• 確認する takes 残高を

This is completely normal in Japanese when one clause contains another clause.

In this grammar pattern, 前に is the fixed form.

• Verb + 前に = before doing ...
• Noun + の + 前に = before ... / in front of ...

Examples:

• 寝る前に = before sleeping
• 食事の前に = before the meal
• 駅の前に = in front of the station

So in your sentence, に is part of the standard pattern 前に.

Because 口座の残高 is more specific: it means the balance of the account or the account balance.

• 口座 = bank account
• 残高 = balance
• 口座の残高 = account balance

You could sometimes just say 残高 if the context is already clear, but 口座の残高 makes it explicit what kind of balance is being checked.

Here の connects two nouns and shows a relationship between them.

• 口座 = account
• 残高 = balance
• 口座の残高 = the account’s balance / account balance

This use of の is extremely common. It often works like:

• possession: 田中さんの本 = Tanaka’s book
• category/type: 日本の車 = Japanese car
• description/relation: 銀行の口座 = bank account

In this sentence, の links account and balance.

確認しました means checked or confirmed, which is more precise than just looked at.

• 見る / 見ました = see, look
• 確認する / 確認しました = check, confirm, make sure

When you look at your account balance before paying rent, you are usually checking it intentionally, not merely seeing it. So 確認しました is the more natural choice.

家賃 usually means rent for a house/apartment/place to live.

So it is commonly used for housing rent. For example:

• 家賃を払う = pay rent
• 家賃が高い = the rent is expensive

If you want to talk about other kinds of rental fees, Japanese may use different words depending on the situation.

Because Japanese normally puts the main verb at the end of the sentence.

The structure is:

• 家賃を払う前に = before paying the rent
• 口座の残高を確認しました = I checked the account balance

The second part is the main statement, so its verb comes at the end.

This is one of the most important word-order features of Japanese: the final verb often tells you the core action of the sentence.

Yes. You could also say:

• 口座の残高を確認してから、家賃を払いました。

That means I checked the account balance, and then paid the rent.

You can also sometimes rearrange parts of the original sentence for emphasis, but the original version is very natural because it frames the main action as:

• Before paying the rent, I checked the account balance.

Japanese often puts time-related information near the beginning.

Because Japanese often omits the subject when it is obvious from context.

So the sentence could be understood as:

• I checked the account balance before paying the rent.

But Japanese does not need to say 私は unless there is a reason to emphasize or clarify who did it.

This is very common in natural Japanese.

Yes. 払う is the standard verb for paying things like:

• 家賃を払う = pay rent
• お金を払う = pay money
• 料金を払う = pay a fee
• 税金を払う = pay taxes

So 家賃を払う is a very natural combination.

Yes. There are two very common patterns:

• Verb dictionary form + 前に
  = before doing something
• Noun + の + 前に
  = before something

Examples:

• 寝る前に = before sleeping
• 出発の前に = before departure
• 昼ご飯の前に = before lunch

So in your sentence, since 払う is a verb, it appears as:

• 払う前に

not

• 払うの前に

It is polite, standard Japanese.

The polite part is:

• 確認しました instead of 確認した

So:

• 確認しました = polite past
• 確認した = plain past

The rest of the sentence is neutral and natural. This kind of sentence would fit well in everyday polite conversation, writing, or explanations.