Je základ daně v souladu s účetní závěrkou?

Je is the 3rd person singular form of být (to be).
So here it means is.

• je = is
• základ daně = the tax base
• v souladu s účetní závěrkou = in accordance with the financial statement(s)

So the sentence structure is basically:

Je + subject + complement?
= Is the tax base in accordance with the financial statement(s)?

Because this is a yes/no question.

A neutral statement would be:

Základ daně je v souladu s účetní závěrkou.
= The tax base is in accordance with the financial statement(s).

To turn it into a yes/no question, Czech often puts the verb first:

Je základ daně v souladu s účetní závěrkou?
= Is the tax base in accordance with the financial statement(s)?

This is very natural and common.

Základ is in the nominative singular because it is the grammatical subject of the sentence.

• základ = base / basis / foundation
• here: the tax base

You can think of it as the thing being asked about:
Is [the tax base] in accordance with ... ?

Because daně is in the genitive singular.

The phrase základ daně literally means:

• základ = base
• daně = of tax

So literally: base of tax, which English normally translates as tax base.

This is a very common Czech pattern:

• základ daně = tax base
• sazba daně = tax rate
• výše daně = amount of tax

Because the noun it depends on, základ, commonly takes a genitive complement to say base of what?

The dictionary form is daň (tax).
Its genitive singular is daně.

So:

• daň = nominative singular
• daně = genitive singular

In this sentence, daně answers the question:

základ čeho? = base of what?
Answer: daně

V souladu s is a fixed expression meaning:

• in accordance with
• consistent with
• in compliance with (depending on context)

It is very common in formal and business Czech.

Examples:

• v souladu se zákonem = in accordance with the law
• v souladu s pravidly = in accordance with the rules

So in your sentence:

v souladu s účetní závěrkou
= in accordance with the financial statement(s)

Because the full expression is v souladu s + instrumental.

So the pattern is:

v souladu s někým / něčím
= in accordance with someone / something

That means the noun after s must be in the instrumental case.

Here the noun is účetní závěrka, and in instrumental singular it becomes:

s účetní závěrkou

Because after s in this expression, Czech uses the instrumental case.

The basic form is:

• účetní závěrka = nominative singular

After s, it changes to instrumental singular:

• s účetní závěrkou

For many feminine nouns ending in -a, the instrumental singular ends in -ou:

• zpráva → se zprávou
• firma → s firmou
• závěrka → se závěrkou / s závěrkou

So:

v souladu s účetní závěrkou
literally = in accordance with the financial statement

Because účetní is an adjective of the soft adjective type, and in this form it looks the same in both nominative singular feminine and instrumental singular feminine.

So:

• účetní závěrka = nominative singular
• s účetní závěrkou = instrumental singular

Only závěrka changes visibly here; účetní stays účetní.

This is normal with adjectives ending in -í.

Grammatically, účetní závěrka is singular in Czech.

However, in English the equivalent is often translated as either:

• financial statement
• financial statements

depending on the accounting context.

So even though the Czech noun is singular, the natural English translation may sometimes be plural. That is a translation issue, not a grammar problem in the Czech sentence.

No. Czech has no articles like a or the.

So Czech simply says:

• základ daně
• účetní závěrka

Whether English needs a, the, or no article at all depends on context.

In this sentence, English usually uses the:

Is the tax base in accordance with the financial statement(s)?

The basic statement is:

Základ daně je v souladu s účetní závěrkou.

That is:

• Základ daně = subject
• je = verb
• v souladu s účetní závěrkou = complement

Then the question version moves the verb to the front:

Je základ daně v souladu s účetní závěrkou?

This is very similar to English Is the tax base ... ?

Yes, Czech word order is more flexible than English, but not every order sounds equally neutral.

The most neutral version here is:

Je základ daně v souladu s účetní závěrkou?

Other orders are possible for emphasis, but they may sound marked, formal, or context-dependent.

For a learner, it is best to keep this standard order unless you have a reason to emphasize something.

Yes, very much so. It sounds like business, legal, tax, or accounting Czech.

Words and phrases like these are typical of formal written or professional language:

• základ daně
• v souladu s
• účetní závěrka

So this is not everyday casual conversation; it belongs to an administrative or professional register.

A rough pronunciation guide is:

yeh ZAA-klad DA-nyeh v SOU-la-du s OO-chet-nyee ZAA-vyer-kou?

A few helpful points:

• Je sounds roughly like yeh
• dě / ně / tě often sound softer than English consonants
• účetní begins with a long ú
• závěrkou has stress on the first syllable, like all Czech words: ZÁ-věr-kou

Czech stress is normally on the first syllable of each word.

A useful breakdown is:

• být → je = to be → is
• základ = base / basis
• daň = tax
• soulad = accord / consistency
• účetní = accounting / financial
• závěrka = closing statement / financial statement

It is especially useful to learn these chunks, not just isolated words:

• základ daně
• v souladu s
• účetní závěrka

Those combinations are very natural and common in formal Czech.