You know both tenses. You have drilled the forms. And yet in a real conversation you still hesitate: I have seen that film or I saw that film? Both are grammatical. Only one is right for the moment, and picking the wrong one is among the most common ways learners sound "off" in English.
The good news is that the choice rests on a single idea, not a pile of exceptions. Once you see it, the rest is practice.
The one-question rule
Ask yourself: is the time period finished, or does it still connect to now?
- If the action belongs to a finished time (yesterday, last year, in 2019, when I was a child), use the Past Simple.
- If the time is unfinished, unspecified, or the action matters for the present, use the Present Perfect.
Compare:
| Situation | Sentence | Why |
|---|---|---|
| Finished time, stated | I saw that film last week. | Last week is over. |
| Time not stated, relevant now | I have seen that film. | We care that you know it now. |
| Unfinished period | I have seen three films this week. | This week is still going. |
| Finished period | I saw three films last week. | Last week is closed. |
How Present Perfect works
The form is have/has + past participle: I have finished, she has gone, they have lived. For irregular verbs you need the third form, which is why the patterns in our guide to English irregular verbs pay off here.
It has three everyday jobs.
1. Life experience (no specific time). The moment is not the point; the experience is.
Have you ever tried sushi? — Yes, I have tried it twice.
2. Unfinished time. The period is still open: today, this week, this year, so far, since, for.
I have lived in Lisbon for six years. (And I still live there.)
3. A past action with a present result. You can see or feel the consequence now.
I have lost my keys. (So I cannot get in.)
How Past Simple works
The form is the second verb form: walked, went, saw. Questions and negatives use did + the base verb: Did you go? and I didn't go.
Use it whenever the action sits at a point or period that is over, and that time is stated or obvious from context:
I lived in Lisbon for six years. (I do not live there anymore.)
Notice how one word, the tense, changes the whole meaning: have lived means you are still there, lived means you have moved on.
Signal words that help (and one that traps)
| Usually Present Perfect | Usually Past Simple |
|---|---|
| ever, never | yesterday |
| already, yet, just | last night / week / year |
| so far, up to now | in 2019, in June |
| since, for | ago (as in two days ago) |
| this week / today / this year | when + a finished event |
The trap is that signal words are hints, not laws. Today can go with either tense: I have had three coffees today (the day is not over) but I had a coffee this morning (the morning is over). Return to the one-question rule whenever a keyword feels ambiguous.
Five mistakes to avoid
- Pairing Present Perfect with a finished time. Wrong: I have seen him yesterday. Right: I saw him yesterday.
- Using the present for an unfinished period. Wrong: I live here since 2020. Right: I have lived here since 2020.
- Asking when with Present Perfect. Wrong: When have you arrived? Right: When did you arrive?
- Mixing tenses in one story. Once you give a specific time, stay in Past Simple: I have been to Rome. I went in May and loved it.
- Forgetting the participle. Wrong: I have went home. Right: I have gone home.
British and American usage
British English leans on Present Perfect for recent news: I've just eaten. American English often accepts Past Simple there: I just ate. Both are fine in everyday speech. For exams and formal writing, follow the textbook rule above and stay consistent.
How to make it stick
Grammar rules you only read fade quickly, which is the same effect described in the forgetting curve. The reliable fix is spaced repetition: save a short sentence for each use, such as I have never been to Japan and I went to Japan in 2019, and review them at growing intervals until the choice feels automatic.
To drill it, add the participles of the irregular verbs you mix up most and run a round of the typing trainer or fill-in-the-blank game with the sentences above. If you are still choosing a level to aim for, our CEFR levels explained guide shows where this contrast usually lands (roughly B1). When you are ready to build your own deck, start from the English course.
Frequently asked questions
Can I use Present Perfect with "yesterday"?
No. Yesterday names a finished time, so use the Past Simple: I saw her yesterday.
What is the difference between "I have lived" and "I lived"?
I have lived here for five years means you still live here. I lived here for five years means you no longer do.
Do "just", "already" and "yet" always need Present Perfect?
In British English, yes in most cases: I have already eaten. American English often uses the Past Simple instead: I already ate. Both are acceptable in conversation.
Which one should I use when I am not sure?
Ask whether the time is finished. If the sentence names a finished time, use the Past Simple. If it names no time or an unfinished one, use the Present Perfect.