Nájemní smlouva není podnájemní smlouva.

A tenancy agreement is not a subtenancy agreement.

Breakdown of Nájemní smlouva není podnájemní smlouva.

• být: to be
• nájemní smlouva: the tenancy agreement
• podnájemní smlouva: the subtenancy agreement

Questions & Answers about Nájemní smlouva není podnájemní smlouva.

What does each word do in this sentence?

• nájemní = an adjective meaning rental / lease-related
• smlouva = contract / agreement
• není = is not
• podnájemní = an adjective meaning sublease / subtenancy-related
• smlouva = again contract / agreement

So the structure is:

[subject noun phrase] + [negative form of “to be”] + [predicate noun phrase]

That is:

Nájemní smlouva + není + podnájemní smlouva

Why is není used here?

Není is the 3rd person singular negative form of být (to be).

• je = is
• není = is not

So:

• Nájemní smlouva je... = A lease contract is...
• Nájemní smlouva není... = A lease contract is not...

This is just the normal Czech way to negate to be.

Why isn’t it neje instead of není?

Because být is irregular.

Its positive and negative forms do not combine in the simple, predictable way that many other verbs do. So although a learner might expect je → neje, standard Czech uses:

• je = is
• není = is not

You simply have to learn není as the correct negative form.