"Sunset" is a converted noun-to-verb, and that history is exactly why its past tense trips people up.
Both are correct: "sunset" (unchanged) and "sunsetted" are equally natural, attested past-tense and past-participle forms -- neither is more correct than the other. This is one of the rare cases in professional English where there's genuinely no wrong answer between two visibly different options.
Why both forms feel wrong to different people
Because sunset is a converted noun-to-verb, learners often either avoid inflecting it at all, or assume the regularly-inflected form "sunsetted" must be wrong because it looks unusual. Both instincts are overcorrections, and both are worth naming explicitly, because they pull in opposite directions.
"We sunset the old plan tiers last year."
The unchanged form above can look like a mistake to a learner who expects every past-tense verb to carry a visible ending -- but it's a fully accepted usage, especially common in passive constructions.
"The legacy portal was sunsetted in March."
The regularly-inflected form above can look wrong to a learner who's absorbed the mistaken idea that sunset must behave like an irregular verb because it doesn't sound like a typical "-ed" verb -- but it's equally accepted, and arguably the more visually intuitive of the two.
Want to learn "Sunset" in depth?
Lyra Practice teaches advanced non-native professionals the nuance of high-value expressions like this one, then has you practice using them in realistic work scenarios.
Start learning for free →"Has the v1 API been sunset yet, or is it still live?"
The only real rule: stay consistent
Native professional usage accepts both forms interchangeably, and neither should ever be marked as an error against the other. The one habit worth building is internal consistency -- pick one form and use it throughout a single document, rather than switching between "sunset" and "sunsetted" mid-page, which reads as inconsistent even though both forms are individually fine.
Don't assume "sunsetted" looks wrong just because it's a fully regular inflection of a converted noun -- and don't assume the unchanged form "sunset" is a mistake either. Both are genuinely interchangeable; just stay consistent within a single document.
Why this word behaves differently from most converted verbs
Plenty of nouns get converted into verbs in business English -- "to email," "to google," "to onboard" -- and most of them settle quickly into one standard past-tense pattern that everyone recognizes. "Sunset" is unusual in that it never fully settled, and both instincts a learner might have (leave it unchanged, like "cut" or "put," or add the regular "-ed," like almost every other converted verb) turn out to be equally supported by real usage.
That's worth knowing not just as a grammar fact, but as a signal about how to read other people's writing: if a colleague writes "sunset" where you might have written "sunsetted," that's not an error to correct, and the reverse is just as true. Save your editing attention for the mistakes that actually are mistakes -- the preposition and person-directed errors covered elsewhere in this batch -- rather than the past tense, which genuinely has two right answers.
Practice scenarios
Practice using sunset in situations like:
- deciding whether to write "sunset" or "sunsetted" in a past-tense sentence
- keeping past-tense forms consistent across one document
- reassuring a colleague that neither form is a mistake
Useful practice phrases:
- "We sunset the old plan tiers last year."
- "The legacy portal was sunsetted in March."
- "Has the v1 API been sunset yet?"
This is one of the rare grammar questions with a genuinely easy answer: both forms work.
The only real mistake is switching between them inside the same document.
Lyra Practice helps advanced non-native English professionals learn the nuance of high-value workplace expressions and practice using them in realistic scenarios, so their English sounds natural, precise, and senior at work. Try Lyra Practice.