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TOEIC Link Part 5 — Owing To vs Due To vs On Account Of: Cause-Preposition Selection

The flight was delayed ____ the storm — owing to, due to, or because of? Part 5 lines up four cause expressions that all mean roughly the same thing but attach to the sentence differently: due to modifies nouns, owing to and because of modify verbs, and all of them take a noun, never a clause. This guide fixes the choice on what the phrase attaches to and what follows the blank, not on meaning, and drills the workplace distractors.

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The shipment arrived late ____ a customs inspection. The options are due to, because, owing, and since. All four are about cause, and all four feel plausible if you read for meaning alone. The intended answer is due to — the others fail on structure: because and since are conjunctions that need a full clause (because a customs inspection **was held**), and owing cannot stand without to. Part 5 rarely tests whether you understand cause; it tests whether you know how each cause expression attaches to the rest of the sentence. This guide sorts the phrasal prepositions — due to, owing to, on account of, because of — from the conjunctions, and settles the one grammar debate the exam still leans on.

The core split: preposition takes a noun, conjunction takes a clause

Every cause word falls into one of two grammar families, and the family decides what can follow the blank:

Phrasal prepositions → followed by a noun (or noun phrase / gerund) due to · owing to · on account of · because of · as a result of

Conjunctions → followed by a full clause (subject + verb) because · since · as

Read the split against one situation:

  • The event was cancelled **because of** the weather. — preposition + noun the weather. ✅
  • The event was cancelled **because** the weather was severe. — conjunction + clause the weather was severe. ✅
  • The event was cancelled **because** the weather. — conjunction with no verb. ❌
  • The event was cancelled **because of** the weather was severe. — preposition dragging a whole clause. ❌

So the first move on any cause item is not which one means "cause" — they all do — but what comes after the blank, a noun or a clause? A noun points to the preposition column; a clause points to the conjunction column. This is the same preposition-versus-conjunction decision that governs despite versus although and during versus while; the cause words are one more instance of the same test.

The one-second test: look right, then look left

Two quick reads settle almost every item.

Look right of the blank first. If a bare noun or gerund follows (the storm, staffing shortages, updating the system), you need a preposition: due to, owing to, on account of, because of. If a subject-plus-verb clause follows (the storm hit, staff were unavailable), you need a conjunction: because, since, as.

Then look left, but only to choose between the prepositions. The classic rule: due to modifies a noun; owing to and because of modify a verb or a whole clause.

  • The delay was **due to** heavy traffic. — due to follows the linking verb was and describes the delay (a noun). Textbook correct.
  • **Owing to** heavy traffic, the delivery was late. — owing to opens the sentence and modifies the whole clause. Due to in this front position is what traditional grammar flags.

In practice, modern business English uses due to freely in both positions, and TOEIC will not usually punish you for it. But when a single item gives you both due to and owing to and the phrase clearly modifies a verb or opens the sentence, owing to is the safer, rule-clean pick.

Sorting the four prepositions by register, not meaning

due to, owing to, on account of, and because of are near-synonyms; the exam separates them by tone and position more than by sense:

  • because of — the neutral, all-purpose default. Works everywhere.
  • due to — slightly more formal; strongest when it follows be and describes a noun (The error was due to a typo).
  • owing to — formal, most natural at the front of a sentence modifying the whole clause.
  • on account of — formal and a touch old-fashioned; common in written notices (Closed on account of the public holiday).

Because they overlap so heavily in meaning, a well-built Part 5 item will not force you to choose among them on sense — it will make three of the four ungrammatical in the slot (wrong family, or missing to, or a following clause) and leave exactly one that fits the structure. Structure decides; register only breaks ties.

Watch the gerund: cause + doing

A frequent trap pairs a cause preposition with an -ing form to see if you'll mistake it for a conjunction:

  • **Owing to** upgrading the servers, the site was briefly offline. — upgrading is a gerund (a noun form), so the preposition owing to is correct.
  • **Because** upgrading the servers, ... — ❌ because needs a finite clause, not a gerund.

If what follows the blank is an -ing word acting as a noun, treat it as a noun: choose a preposition, not a conjunction. Spotting whether an item is testing structure or vocabulary — the family of the following word versus its meaning — is the habit behind every Part 5 point, laid out in word choice versus word form: knowing which question you are answering. And when the cause clause is contrasted with an expected outcome, the same preposition-versus-conjunction logic reappears in despite versus although: preposition-conjunction selection.

Workplace drill: choose the correct cause word

  1. The quarterly review was postponed ____ a scheduling conflict. (noun follows) → due to / because of / owing to / on account of — any preposition; not because (no clause).
  2. Sales rose sharply ____ the new pricing tiers were introduced. (clause follows) → because / since / as — a conjunction; not due to.
  3. ____ the ongoing renovation, the lobby entrance is closed. (front position, whole-clause modifier, noun follows) → Owing to / Because of / On account of — front-position prepositions.
  4. The outage was ____ a failed database migration. (follows was, describes the outage, noun follows) → due to — the textbook noun-modifying slot.
  5. We rescheduled the demo ____ integrating the new API took longer than planned. (gerund-led clause? read carefully — integrating ... took is a full clause) → because / since — a conjunction, because the -ing word here is the subject of a finite verb took.

Item 5 is the sharpest one: integrating looks like a gerund you could hang a preposition on, but it is the subject of the verb took, which makes the whole thing a clause — so you need a conjunction, not a preposition. Read to the verb before you decide. Look right for noun-or-clause, look left only to break ties between prepositions, and the cause words stop being interchangeable and start being a structure test you can win every time.