Irregular verbs and "should have"
Use the right form of irregular verbs, and write should have, never should of.
Updated October 29, 2026
The rule
Many common verbs don't add -ed: go, went, have gone; see, saw, have seen; write, wrote, have written. After has, have or had, use the third form (gone, seen, written).
Could of, should of and would of are mishearings of could've, should've and would've: write have. Lie means to recline (lay, lain); lay means to put something down (laid).
Examples
I should of called you.I should have called you.She has went home already.She has gone home already.
Quick test: If you hear "of" after could, should or would, it is always "have".
Try it: find the mistake
The mistake in each sentence is highlighted. Say the fix out loud, then open the answer.
I should of brought a jacket.
I should have brought a jacket.
It is should have (or should've), never should of.
We seen a shooting star last night.
We saw a shooting star last night.
The past of see is saw. Seen needs have before it.
She has wrote three songs this month.
She has written three songs this month.
After has, use the third form: has written.
I was so tired that I laid down on the couch.
I was so tired that I lay down on the couch.
To recline is lie; its past is lay. Laid means "put something down".
Where this rule is tested
Questions people ask
What is the rule for irregular verbs and "should have"?
Use the right form of irregular verbs, and write should have, never should of. Many common verbs don't add -ed: go, went, have gone; see, saw, have seen; write, wrote, have written. After has, have or had, use the third form (gone, seen, written).
How can I check my irregular verbs and "should have" quickly?
If you hear "of" after could, should or would, it is always "have".
Where can I practice this for free?
In Owl Test Prep's Daily Grammar Fix: one sentence a day for everyone, plus practice sets of five on this rule. It is free, with no account.