Het variabele tarief verandert elke maand.

Because tarief is a het-word in Dutch, which means it takes the definite article het in the singular: het tarief.

A few useful patterns:

• singular definite: het tarief
• plural definite: de tarieven
• indefinite singular: een tarief

Unfortunately, whether a noun is a de-word or a het-word often just has to be learned with the noun.

The basic adjective is variabel. It becomes variabele here because it comes before a noun and modifies it: het variabele tarief.

Dutch adjectives usually take -e before a noun. Compare:

• een variabel tarief = an variable rate / a variable rate
• het variabele tarief = the variable rate

This is an important pattern:

• after het, adjectives normally take -e
• after de, adjectives also normally take -e

So variabel is the dictionary form, and variabele is the form used here before tarief.

Because the verb is veranderen and the subject is het variabele tarief, which is third-person singular.

Present tense of veranderen:

• ik verander
• jij verandert
• u verandert
• hij/zij/het verandert
• wij veranderen
• jullie veranderen
• zij veranderen

Since het variabele tarief is grammatically like it, you use verandert.

Yes. Verandert is present tense.

In this sentence, the present tense expresses something that happens regularly or as a general fact:

• Het variabele tarief verandert elke maand.

So it means the rate changes month after month, not just right now at this exact second.

This is very normal in Dutch, just as in English:

• The store opens at 9.
• The variable rate changes every month.

Elke maand means every month and tells you how often the change happens.

It is a time expression. In this sentence, it comes after the verb:

• Het variabele tarief verandert elke maand.

That is a very natural word order in Dutch.

You can move time expressions around for emphasis, for example:

• Elke maand verandert het variabele tarief.

That is also correct, but the original version is the most neutral.

Yes. Elke maand and iedere maand both mean every month.

So these are both correct:

• Het variabele tarief verandert elke maand.
• Het variabele tarief verandert iedere maand.

In everyday Dutch, elke is often a bit more common, but both are standard and natural.

Because elke already functions as a determiner, a bit like every in English.

So Dutch says:

• elke maand = every month

and not:

• de elke maand
• een elke maand

Just like English says every month, not the every month.

Here, variabele is an adjective, describing tarief.

So:

• variabel = variable
• tarief = rate
• variabele tarief = variable rate

Be careful, because variabele can also be a noun in other contexts, meaning variable in the mathematical or technical sense:

• een variabele in een formule = a variable in a formula

But in your sentence, it is clearly an adjective.

A rough pronunciation guide:

• Het ≈ hut / ut
• variabele ≈ va-ree-AH-buh-luh
• tarief ≈ ta-REEF
• verandert ≈ vuh-RAN-durt
• elke ≈ EL-kuh
• maand ≈ maand, with a long aa

A few notes:

• The stress is usually on -rieef in tarief.
• In variabele, the stress falls around a/ri-a depending on speech rhythm, but learners often do fine if they say it clearly in syllables.
• Final -e in Dutch is usually a soft uh sound.

Yes, Dutch word order is flexible, especially with time expressions.

The neutral version is:

• Het variabele tarief verandert elke maand.

You can also say:

• Elke maand verandert het variabele tarief.

When you put Elke maand first, the verb must still stay in second position, so verandert comes right after it. This is a key Dutch word order rule.

If you wanted to make it plural, you would change both the noun and the verb:

• singular: Het variabele tarief verandert elke maand.
• plural: De variabele tarieven veranderen elke maand.

Changes:

• het tarief → de tarieven
• verandert → veranderen

The adjective variabele stays the same before the plural noun.

Dutch often uses the simple present where English might use either:

• changes
• is changing

In this sentence, Dutch simply says:

• verandert

That is enough to express a habitual or regular action. If the idea is it changes every month, the simple present is exactly what Dutch normally uses.

So this sentence sounds natural and standard Dutch.