Niedopłata jest mała.

Because mała has to agree with niedopłata.

• niedopłata is a feminine singular noun.
• Polish adjectives change their form to match the noun in gender, number, and usually case.
• So the adjective is mała:
  • mały = masculine singular
  • mała = feminine singular
  • małe = neuter singular

So Niedopłata jest mała is grammatically matched.

A very common clue is the ending -a.

Most Polish nouns ending in -a are feminine, and niedopłata follows that pattern. Because it is feminine, any adjective describing it also takes a feminine form, such as mała.

This is why the sentence uses mała, not mały.

Jest is the 3rd person singular present tense of być, meaning to be.

So here it works like English is.

• niedopłata = subject
• jest = is
• mała = predicate adjective

So structurally, it is simply:

[subject] + [is] + [adjective]

Normally, no.

In standard Polish, when you say that something is a certain way, you usually keep jest:

• Niedopłata jest mała.

Leaving it out would sound incomplete or very non-standard in an ordinary sentence like this.

Polish sometimes omits forms of to be in very informal speech, notes, slogans, or poetic style, but for normal learning and normal grammar, you should keep jest here.

It is in the nominative case because it is the subject of the sentence.

Also, mała is nominative too. With być plus an adjective, Polish uses the adjective in the nominative:

• Niedopłata jest mała.

A learner may wonder whether it should be something like małą, but that would be wrong here. Predicative adjectives with być stay in the nominative.

Because Polish does not have articles.

English needs words like a and the, but Polish usually does not. So:

• Niedopłata jest mała.

can mean things like:

• The underpayment is small
• An underpayment is small

Which one is meant depends on the context.

Yes, Polish word order is more flexible than English word order, but the neutral order here is:

• Niedopłata jest mała.

That is the most natural, straightforward version.

You can change the order for emphasis, but then the focus changes. For example, moving mała forward would sound marked or stylistic, not neutral everyday word order.

So as a learner, the best default is to keep:

• Niedopłata jest mała.

Because mała is an adjective, and this sentence is describing a quality.

In Polish, to is commonly used when you connect two nouns or noun phrases, for example:

• To jest problem.
• Jan to lekarz.

But with an adjective like mała, you normally use jest:

• Niedopłata jest mała.

So to would not be the normal choice here.

A simple learner-friendly approximation is:

• niedopłata ≈ nyeh-doh-PWAH-tah
• jest ≈ yest
• mała ≈ MAH-wah

A few important pronunciation points:

• ł is pronounced like English w in modern Polish.
  • So mała sounds roughly like mawa, not mala.
• Stress usually falls on the second-to-last syllable:
  • nie-do-PŁA-ta
  • MA-ła

Yes.

• dopłata is an extra payment, an additional amount to pay, or a surcharge/top-up depending on context.
• niedopłata refers to a situation where too little has been paid, so there is still some amount missing.

So the word is built from familiar Polish pieces, and recognizing that can help you remember it.

Yes, often you can.

• mała = small
• niewielka = small / not large / slight

Both can work, but niewielka often sounds a bit more formal or a bit more polished. So:

• Niedopłata jest mała.
• Niedopłata jest niewielka.

Both are natural, though mała is the simpler, more basic adjective for a learner.

You put nie before jest:

• Niedopłata nie jest mała.

That means the underpayment is not small.

This is the normal way to negate a sentence with być in Polish:

• jest → nie jest