Verb Tenses
Future perfect
By + future time often pairs with will have + past participle.
Why this happens
Future perfect (will have + past participle) marks completion before a future deadline, but it is uncommon, so writers avoid it or build it wrong (will have went). Use it with by next week, by then, or before + future time when finishing before that moment is the point.
See it in a sentence
IncorrectBy Friday I will finished the report.
CorrectBy Friday I will have finished the report.
Teaching note: Future completion before a deadline uses will have + past participle.
IncorrectShe will has completed the course by June.
CorrectShe will have completed the course by June.
Teaching note: After will, use have — not has.
IncorrectBy 2030, scientists will discover a cure — if meaning completed by then.
CorrectBy 2030, scientists will have discovered a cure.
Teaching note: By 2030 points to completion — future perfect will have discovered.
More examples
By the time you read this, I will have left.
Reader's future moment follows the completed action.
In two years she will have worked here for a decade.
Duration counted up to a future point.
Future perfect is rare in everyday speech — simple future often replaces it.
I will finish by Friday is acceptable if completion is clear.
Will have been is future perfect continuous — different emphasis on duration.
Do not confuse will have done with will have been doing.
Quick check
By next month, they will complete all migrations.
Show the fix
By next month, they will have completed all migrations — if stressing done before that date. Will have completed marks completion by the deadline.
Practice this topic in Wrytesmart
Open the grammar workspace to complete interactive exercises for future perfect. You will spot errors, fill blanks, and transform sentences — always with teaching notes that explain the principle, not just the correction.
Master future perfect in context
Free to start. Sign in to save progress and get adaptive drills linked to your writing.