Learn Hardcore Icelandic: Hún biður um leyfi til að fara fyrr. - She asks for permission to leave earlier.

að biðja um e-ð (acc.) = to ask for something. Example: Hún biður um leyfi (She asks for permission).
að spyrja (e-n) um e-ð / að spyrja (e-n) = to ask (someone) a question or to ask about something. Example: Hún spyr hvort hún megi fara fyrr (She asks whether she may leave early). Using spyrja here would change the meaning to “ask about permission,” not “ask for permission.”

Why is the preposition um used here, and which case does it take?

um means “for/about” and it governs the accusative case. In um leyfi, the noun is in the accusative. You can’t see the case ending here because leyfi looks the same in nominative and accusative singular (it’s a neuter noun), but grammatically it’s accusative.

Why doesn’t leyfi change form here? What are its forms?

leyfi is a neuter noun that is the same in nominative, accusative, and dative singular. Its genitive singular and plural forms change:

Singular: nom/acc/dat leyfi, gen leyfis
Plural: nom/acc leyfi, dat leyfum, gen leyfa Here, um demands the accusative, so it’s accusative singular leyfi (unchanged in form).

Can I say Hún biður um að fara fyrr instead? Is it the same meaning?

Yes. Hún biður um að fara fyrr = “She asks to leave early.” It usually implies asking for permission, but it doesn’t explicitly mention “permission.”
Hún biður um leyfi til að fara fyrr makes the permission explicit and a bit more formal/clear.

Why is it leyfi til að fara, not leyfi að fara?

Icelandic says “permission to do something” as leyfi til að + infinitive. The til is required here; leyfi að fara is ungrammatical.
A slightly more explicit variant is leyfi til þess að fara (literally “permission for that to go”).

What does til að do here? Does til still require the genitive?

til að + infinitive introduces a purpose clause (“in order to”). When til is followed by að + verb, it’s part of this fixed construction, not followed by a noun, so you don’t see a genitive noun after it.
If til takes a noun, it requires the genitive: e.g., leyfi til brottfarar (“permission for departure,” genitive brottfarar).

How do I conjugate biðja (to ask) in the forms I’m most likely to need?

Present: ég bið, þú biður, hún biður, við biðjum, þið biðjið, þau biðja
Past (3rd person): hún bað (she asked), þau báðu (they asked)
Supine/participle used with “have”: hún hefur beðið (she has asked) This verb is irregular (stem changes: bið- / bað- / beð-).

Does fara mean “to go” or “to leave” here? And why fyrr instead of snemma?

fara can mean “to go” or “to leave,” depending on context; here it’s “leave.”

fyrr = “earlier/sooner,” i.e., earlier than some usual or expected time.
snemma = “early” in an absolute sense (not comparative).
Since the idea is “earlier than usual” (leave early), fara fyrr is the natural choice.

What’s the difference between fyrr, fyrir, and fyrri?

fyrr: adverb, “earlier/sooner” (comparative). Example: að fara fyrr (to leave earlier).
fyrir: preposition “for/before/because of” (takes different cases depending on meaning). Not used here.
fyrri: comparative adjective “former/earlier” used with nouns. Example: á fyrri árum (in former years). Don’t mix up fyrr (adverb) with fyrir (preposition).

Where does fyrr go in the infinitive phrase? Can it move?

In að fara fyrr, the adverb fyrr naturally follows the verb. Placing it before the verb (að fyrr fara) is nonstandard in modern prose and would sound poetic or odd. So keep fyrr after fara.

How do I add the person she is asking?

Use the pattern biðja e-n (ACC) um e-ð:

Hún biður yfirmanninn um leyfi til að fara fyrr.
“yfirmanninn” (the boss) is the person being asked, in the accusative.

Are there simpler, everyday ways to ask for permission to leave early?

Yes, very common and natural:

Má ég fara fyrr? (May I leave early?)
Get ég farið fyrr? (Can I leave early?)
Er í lagi að ég fari fyrr? (Is it okay if I leave early?)
Your original sentence is fine, just a bit more formal/explicit.

How would this look in the past, progressive, or future?

Past: Hún bað um leyfi til að fara fyrr.
Progressive-like (ongoing): Hún er að biðja um leyfi til að fara fyrr.
Future-like: Hún mun biðja um leyfi til að fara fyrr.

Why not use the definite form leyfið?

leyfið means “the permit/the permission” (definite). In the abstract sense (“permission” in general), Icelandic usually uses the indefinite leyfi.
Use leyfið when referring to a specific permit/document, e.g., Hún biður um leyfið = “She asks for the (specific) permit.”

Could I use fyrir instead of um: Hún biður fyrir leyfi?

No. biðja fyrir means “to pray for” (among other meanings), not “ask for.” The idiom for “ask for (something)” is biðja um (e-ð). So you need um, not fyrir.

Can I add það after um or til?

Yes:

Hún biður um það að fara fyrr. (natural, though often the það is omitted)
Hún biður um leyfi til þess að fara fyrr. (perfectly idiomatic; til þess að is a common variant of til að)

Any quick pronunciation tips for key words here?

Hún: long ú (like “oo” in “food”).
biður: ð is like the “th” in “this.”
leyfi: ey sounds like “ay” in “say”; the f between vowels is pronounced like a v.
fara: clear rolled/trilled r.
fyrr: double consonant effect shortens the preceding vowel; the y is a fronted “u”-like sound.