Learn Hardcore Icelandic: Samningurinn verður undirritaður aftur á morgun. - The contract will be signed again tomorrow.

Yes. Verður undirritaður is an eventive passive: verða (here 3rd person singular present verður) + a past participle (undirritaður, “signed”). Literally it’s “becomes signed,” but idiomatically it’s “will be signed.” Icelandic often uses the present tense with time words (like á morgun) to refer to the future.

Why is the noun in the nominative (Samningurinn) and not samninginn?

Because Samningurinn (“the contract”) is the grammatical subject of the passive clause, so it’s in the nominative. Samninginn is accusative and would be used as a direct object in an active or impersonal construction, e.g. Þeir munu skrifa undir samninginn á morgun (“They will sign the contract tomorrow”).

Why does the participle end in -ur (undirritaður)?

Agreement. The past participle functions like an adjective and agrees with the subject in gender, number, and case. Samningurinn is masculine singular nominative, so the participle is undirritaður. Other forms:

Feminine singular nominative: undirrituð (e.g. Yfirlýsingin verður undirrituð).
Neuter singular nominative/accusative: undirritað (e.g. Skjalið verður undirritað).

How would this look in the plural?

With a plural subject you use plural agreement on the participle: Samningarnir verða undirritaðir aftur á morgun (“The contracts will be signed again tomorrow”). Masculine plural nominative of the participle is undirritaðir.

Could I use vera instead of verða? What’s the difference?

verða + participle (eventive passive): focuses on the action happening/being carried out. Fits “will be signed.”
vera + participle (stative passive): describes a resulting state. Samningurinn er undirritaður = “The contract is (in the state of being) signed.”
So for “will be signed,” verða is the natural choice.

Is there a version with the -st (middle) form?

Yes: Samningurinn undirritast á morgun. The -st form often corresponds to a passive-like meaning (“gets signed / is signed”) and is common and idiomatic. It’s close in meaning to verður undirritaður here.

Why is there no separate word for “will”?

Icelandic has no dedicated future tense. The present is used with a future time expression (á morgun) or with the auxiliary munu. You could say Samningurinn mun verða undirritaður á morgun, but it’s not necessary; the original is perfectly natural.

Where do the adverbs go? Is the order “undirritaður aftur á morgun” fixed?

Adverb placement is flexible. Common options include:

Samningurinn verður aftur undirritaður á morgun.
Samningurinn verður undirritaður aftur á morgun.
Á morgun verður samningurinn (aftur) undirritaður.
All keep verb-second word order (the finite verb verður stays in second position). Aftur typically appears before or after the participle; both are fine.

How do I negate this?

Place ekki after the finite verb: Samningurinn verður ekki undirritaður á morgun (“The contract will not be signed tomorrow”). If you keep aftur, a natural version is Samningurinn verður ekki undirritaður aftur á morgun.

How can I add who will sign it (the agent)?

Use af + dative after the participle:

Samningurinn verður undirritaður af lögfræðingnum á morgun (“…by the lawyer”).
…af fyrirtækinu (“…by the company”), …af mér (“…by me”), etc.

Could I say this more colloquially with “skrifa undir” instead of “undirrita”?

Yes, but you’ll usually use an impersonal passive: Það verður skrifað undir samninginn á morgun (“There will be signing of the contract tomorrow”). The version Samningurinn verður skrifaður undir is uncommon; use undirritaður or undirskrifaður for a subject-based passive.

What’s the difference between á morgun and í morgun?

á morgun = “tomorrow.”
í morgun = “this morning.”
Related: á morgnana = “in the mornings” (habitual).

What case is morgun in, and why isn’t it morgunn here?

In á morgun, morgun is accusative singular after á in a time expression. The nominative form is morgunn, but prepositional time phrases like this use the accusative, hence morgun.

Why is the verb form verður and not verð or verða?

Agreement with the subject. Samningurinn is 3rd person singular, so verður (3rd sg. present). Forms of verða (present):

1sg verð, 2sg verður, 3sg verður, 1pl verðum, 2pl verðið, 3pl verða.

Can I front the time phrase?

Yes: Á morgun verður samningurinn undirritaður aftur. Icelandic is verb-second, so when you front Á morgun, the finite verb verður still stays in second position.

Any quick pronunciation tips for tricky letters here?

ð in verður/undirritaður is like English “th” in “this.”
r is tapped or trilled.
Primary stress is on the first syllable of words: SAM-ningurinn, VER-ður, UND-ir-rit-a-ður, Á MOR-gun.