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TOEIC Link Part 5 — Complementary vs. Complimentary: The Confusable Pair That Costs You a Free Upgrade

Complementary and complimentary sound almost identical and differ by a single letter, but they mean two completely unrelated things — one is about completing, the other is about praising or giving away for free. TOEIC Link Part 5 loves this pair because a business context can plausibly fit either word until you check the actual meaning. This guide fixes the distinction for good with a memory hook, business examples, and a two-second test.

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TOEIC Link Part 5 — Complementary vs. Complimentary: The Confusable Pair That Costs You a Free Upgrade

Say complementary and complimentary out loud. In fast business speech they are nearly indistinguishable, and in writing they differ by exactly one letter — an e versus an i in the middle. That single letter is the whole difference in meaning, and the two words are not variants of one idea: they come from two unrelated roots and point in two different directions. TOEIC Link Part 5 uses this pair precisely because a plausible business sentence can accept either spelling at a glance, and only a test-taker who actually knows the meanings can pick the right one.

This is a high-value pair to lock down because the confusion is common even among native business writers, and the test rewards the distinction directly. It sits in the same family of one-letter traps as affect versus effect, where a tiny surface difference hides a complete change of meaning.

Complementary: completing or matching

Complementary (with an e) comes from complement — the thing that completes or perfectly matches something else. If two things are complementary, they go together and each supplies what the other lacks.

  • "The new marketing hire brings complementary skills to the engineering-heavy team." (Her skills complete the gap.)
  • "We offer a complementary range of services that work together." (They match and combine.)
  • "The two proposals are complementary rather than competing." (They fit together.)

The memory hook: complEmentary contains complEte. Both have that e, and both are about completing or matching. If you can replace the word with "completing" or "matching" and the sentence still makes sense, you want the e spelling. This is the same noun-and-verb pair covered in the complement versus compliment guide — the -ary adjective simply carries the same meaning into descriptive position.

Complimentary: praising, or given free of charge

Complimentary (with an i) comes from compliment — an expression of praise. It has two everyday business senses:

  1. Expressing praise. "The client was complimentary about the redesign." (She praised it.)
  2. Given free of charge. "Guests receive a complimentary breakfast." "We included a complimentary upgrade." (No charge — the item is given as a courtesy, almost as a compliment to the customer.)

The second sense is the one TOEIC Link tests most, because "free of charge" fits so naturally into commercial contexts — hotels, airlines, subscriptions, and promotions all offer complimentary things. The memory hook: complImentary — an i for "it's free" and for the praise you'd give when you receive it.

The two-second test

When you meet the word in a Part 5 sentence, ask one question: is this about completing/matching, or about free/praise?

  • Completing or matching → complEmentary (e, like complEte)
  • Free of charge or praising → complImentary (i)

Try it. "The airline offered a __ shuttle to the hotel." The shuttle is free, so it is complimentary (i). "The wine was chosen to be __ to the meal." The wine matches the meal, so it is complementary (e). Two nearly identical words, two questions apart.

Why the distractor works on the test

Part 5 items exploit the fact that a single business sentence often could host either meaning if you don't read carefully. "The hotel provides a __ fruit basket to every guest." A rushed reader sees "hotel" and "guest" and picks whichever spelling looks familiar. But the sentence is about something given free — so only complimentary (i) is correct. The wrong option is deliberately the spelling you'd reach for on autopilot.

The defense is the habit itself: never choose between this pair by how the word looks. Run the meaning test every time. This is the same discipline that separates the winners from the losers across the whole confusable-pairs family — the surface is a trap, and the meaning is the only reliable guide.

A drill to make it automatic

Write four sentences of your own — two where something is completing or matching another thing, and two where something is free or being praised. Fill in the blank with the correct spelling, then check: did the e land on the "complete/match" sentences and the i on the "free/praise" sentences? Do this once and the pair separates cleanly in your memory, because you will have physically linked each spelling to its meaning rather than to its look.

On test day the payoff is direct: one letter, one meaning check, one guaranteed point on a pair that catches everyone who trusts their eyes instead of the definition.