El periodo de facturación termina mañana.

Because periodo is a masculine noun in Spanish, so it takes el.

A good general rule is:

• nouns ending in -o are often masculine
• nouns ending in -a are often feminine

So:

• el periodo
• el periodo de facturación

Even though English period does not have grammatical gender, Spanish nouns do.

Both periodo and período are accepted spellings.

The difference reflects pronunciation:

• periodo → usually pronounced in 3 syllables
• período → usually pronounced in 4 syllables

You may see either form depending on region, style, or personal preference. In this sentence, periodo is correct.

Literally, de facturación means of billing or related to billing.

So:

• periodo = period
• facturación = billing / invoicing

Together, periodo de facturación means billing period or billing cycle.

This is a very common Spanish structure:

• noun + de + noun

Examples:

• tarjeta de crédito = credit card
• centro de salud = health center
• periodo de facturación = billing period

Facturación comes from facturar, which means to bill or to invoice.

So facturación refers to:

• billing
• invoicing
• the process of charging a customer

In business, subscription, banking, and telecom contexts, facturación is very common.

Spanish often uses the present tense to talk about a scheduled or expected future event, especially when there is a clear time expression like mañana.

So:

• El periodo de facturación termina mañana. means the same idea as
• The billing period ends tomorrow.

This sounds natural in both Spanish and English.

Spanish also allows:

• El periodo de facturación terminará mañana.

That version is more explicitly future, but termina mañana is completely normal and very common.

Yes. That is also correct.

The difference is mostly one of style and tone:

• termina mañana = very natural, everyday, often used for schedules
• terminará mañana = a bit more explicitly future, sometimes slightly more formal or emphatic

In many contexts, both are interchangeable.

Because mañana can function as a time adverb, meaning tomorrow.

Spanish often uses time words directly:

• hoy = today
• mañana = tomorrow
• ayer = yesterday

So you simply say:

• termina mañana
• llega hoy
• salió ayer

No extra preposition is needed.

Here it means tomorrow.

Mañana can mean two different things:

• mañana = tomorrow
• la mañana = the morning

In this sentence, since it appears by itself as a time adverb after the verb, the meaning is tomorrow.

Compare:

• Termina mañana. = It ends tomorrow.
• Termina en la mañana. = It ends in the morning.

Yes. Spanish word order is flexible.

You can say:

• El periodo de facturación termina mañana.
• Mañana termina el periodo de facturación.

Both are correct.

The first version is more neutral and straightforward. The second puts more emphasis on mañana.

Periodo de facturación is natural and correct.

Another very common option is:

• ciclo de facturación = billing cycle

In many real-life contexts, especially subscriptions, utilities, phone service, or software, ciclo de facturación may sound even more common.

So these are both good:

• El periodo de facturación termina mañana.
• El ciclo de facturación termina mañana.

Facturación is pronounced with the stress on the last syllable because of the written accent:

• fac-tu-ra-CIÓN

A simple English-friendly guide:

• fahk-too-rah-SYON in much of Latin America

The ción ending is very common in Spanish and usually corresponds to English -tion:

• información
• confirmación
• facturación

Normally, no. In a full sentence, you would usually keep the article:

• El periodo de facturación termina mañana.

Without el, it sounds incomplete or headline-like.

Spanish uses articles more often than English in many cases, so el is important here.

It is neutral and standard.

It would sound natural in:

• customer service messages
• billing notices
• websites and apps
• emails from a company

It is neither overly formal nor casual, which makes it very useful for everyday business Spanish.