nyuutouzei wo harau.

It is read にゅうとうぜい.

• 入湯 = にゅうとう, literally entering hot water / bathing in a hot spring
• 税 = ぜい, meaning tax

So 入湯税 is the special tax charged when using certain hot spring facilities.

を marks the direct object of the verb.

In 入湯税を払う, the thing being paid is 入湯税, so it takes を.

• 入湯税 = the bathing tax
• を = object marker
• 払う = to pay

So grammatically, it is [tax] + を + [pay].

払う（はらう） is a very common verb meaning to pay.

It is often used for:

• taxes
• fees
• money in general
• bills

Examples:

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

A related verb is 支払う（しはらう）, which is a bit more formal or businesslike. In everyday language, 払う is very natural here.

The dictionary form is the basic plain form of the verb.

In Japanese, a short phrase like 入湯税を払う may appear in:

• a vocabulary list
• a sign
• a heading
• a sentence fragment
• a plain-style sentence

It can mean something like:

• to pay the bathing tax
• pay the bathing tax

If you wanted a polite full sentence, you could say:

• 入湯税を払います。

If you wanted past tense:

• 入湯税を払った。 = paid the bathing tax
• 入湯税を払いました。 = paid the bathing tax

Yes, the subject is omitted, and that is very normal in Japanese.

Japanese often leaves out information that is clear from context. So 入湯税を払う could mean:

• I pay the bathing tax
• you pay the bathing tax
• we pay the bathing tax
• to pay the bathing tax

depending on the situation.

If you wanted to state the subject, you could say:

• 私は入湯税を払う。 = I pay the bathing tax.

But in many contexts, 私は would be unnecessary.

It is not an everyday word for all situations, but it is common in the context of:

• hot springs
• onsen towns
• hot spring hotels
• travel information

If you stay at an onsen inn in Japan, you may see or hear this word when they explain extra charges.

For example:

• 入湯税は別です。 = The bathing tax is separate.
• 入湯税をお支払いください。 = Please pay the bathing tax.

So it is a practical word, especially for travelers.

Yes.

• 入 = enter
• 湯 = hot water
• 税 = tax

So the word literally has the idea of a tax for entering/using hot spring bathing facilities.

That literal breakdown can help you remember it, even though in practice you should learn 入湯 as one unit here.

This is a Sino-Japanese reading, using the on’yomi readings of the kanji:

• 入 → にゅう
• 湯 → とう

So:

• 入湯 → にゅうとう

This is a good reminder that many compound nouns in Japanese use on’yomi rather than the native Japanese readings.

For example, even though 入る is はいる and 湯 can be ゆ, the compound does not become something like はいるゆ. It becomes にゅうとう.

Yes, 入湯税を支払う（しはらう） is also correct.

The difference is mostly nuance:

• 払う = common, straightforward, everyday
• 支払う = more formal, official, businesslike

So:

• 入湯税を払う sounds natural and ordinary
• 入湯税を支払う sounds a bit more formal

Both are grammatically fine.

Some natural polite versions are:

• 入湯税を払います。
  I will pay / pay the bathing tax.

• 入湯税をお支払いください。
  Please pay the bathing tax.

• 入湯税は現地で払います。
  You pay the bathing tax on-site.

• 入湯税がかかります。
  A bathing tax applies.

In real-life travel situations, you will often see 入湯税がかかります or 入湯税は別途必要です rather than just the plain dictionary form.

It can be understood as either, depending on context.

As written with 。, it can function as a plain-style sentence:

• (I/you/we) pay the bathing tax.

But it is also very natural as a phrase meaning:

• to pay the bathing tax

Japanese often uses dictionary-form phrases on:

• lists
• forms
• instructions
• notes
• study materials

So if you saw 入湯税を払う by itself in a textbook or vocabulary list, it is probably being shown as a verb phrase rather than a full context-rich sentence.