Present Perfect vs Simple Past
Choose the tense by locating the sentence's reference time: a finished past period, or a period and consequence that reach the present.
Quick Answer
Use the simple past for an event or state placed inside a finished past time: We signed the contract in March.
Use the present perfect to look back from now: for an unfinished time period, an experience up to now, a state continuing now, or a past event whose result matters now: We have signed the contract, so work can begin.
🔑 Key Takeaway
Do not ask only whether the action is complete. Ask whether the reference time is finished. A completed action can still take the present perfect when its result is the point of the sentence.
Start with the Reference Time
The two forms do different timekeeping. The simple past places a situation on a past timeline. The present perfect looks backward from the present and connects the earlier situation to now. British Council describes this connection through unfinished periods, life experience, continuing states, and present results.
| Question to ask | Simple past | Present perfect |
|---|---|---|
| Is the event located in a finished time? | We sent the invoice yesterday. | Not with yesterday as the event's time. |
| Is the reporting period still open? | We sent three updates this morning. (the morning is over) | We have sent three updates this morning. (it is still morning) |
| Does a state continue to now? | She lived here for two years before moving. | She has lived here since 2020. (she still lives here) |
| Is this experience up to now or a dated visit? | I visited Lisbon in 2024. | I have visited Lisbon twice. |
| Is the present result the point? | Leo lost the key on Monday. | Leo has lost the key, so we cannot enter. |
The same event can therefore be reported in two ways. Mina repaired the server at 10:15 records when it happened. Mina has repaired the server, so deployments can resume reports the present result. Neither tense is inherently more formal or credible.
Three Boundaries That Prevent Bad Shortcuts
1. A named time is not automatically a ban
A finished-time expression that locates the event normally selects the simple past: The archive opened in 1998. But a sentence may contain that date without using it as the time of the present-perfect event: The archive, which opened in 1998, has served the community for decades. The relative clause dates the opening; the main clause describes a span reaching now.
2. “Today” and “this week” depend on the speaker's window
British Council contrasts finished adverbials such as yesterday and last year with periods that are not yet finished, such as today and this week. The clock word alone is not enough. At 10 a.m., I have answered six messages this morning treats the morning as open. At 4 p.m., I answered six messages this morning treats it as closed.
3. Since and for describe a boundary, not a tense by themselves
Since 2020 supplies a starting point and usually supports the present perfect when the state continues: Ravi has worked here since 2020. A completed duration uses the simple past: Ravi worked here for four years before leaving. This page compares the simple present perfect with the simple past; continuous forms require a separate activity-versus-result decision.
Common Repairs
I have finished the report yesterday.
I finished the report yesterday.
She lived in Busan since 2021. (she still lives there)
She has lived in Busan since 2021.
We have launched the service in May and have supported it since then.
We launched the service in May and have supported it since then.
🎯 Test the Time Window
1. “We ___ the revised plan last Friday.”
2. “The team ___ 18 requests so far.”
3. “She ___ there for five years before she moved.”
4. “I ___ Seoul twice.” (life experience up to now)
5. “We ___ in May and ___ customers since then.”
Live Check: A Time Error the Checker Missed
On July 16, 2026, Grammarlyzer returned no issues for the exact sentence below, even though yesterday calls for the simple past in this meaning. The checker also returned no issues for the manual revision, I finished the report yesterday.
Manual review: I finished the report yesterday.
In the two recorded submissions, both the finished-time error and its manual repair returned no issues. Those results do not establish whether the checker evaluated other open or closed time windows or completed-residence contexts. Preserve that context during manual review.
What the Direct Sources Support
British Council's present perfect lesson covers unfinished periods, life experience, continuing states with since and for, present results, and the switch to simple past when the time is stated or considered finished.
British Council's past-time reference explicitly separates finished adverbials such as yesterday and in 2010 from time periods viewed as unfinished. Cambridge's comparison provides an additional direct reference for the same contrast.
These sources describe normal tense choices; they do not justify claims that one tense is always more professional, that a tense switch is automatically inconsistent, or that one adverb mechanically determines every sentence. Those shortcuts have been excluded here.
Frequently Asked Questions
Can I use the present perfect with yesterday or a finished date?
Can today or this week take either tense?
Do since and for always require the present perfect?
Do ever, never, already, and yet force the present perfect?
Did the Grammarlyzer checker catch the finished-time error in the demo?
A Five-Step Tense Audit
- Underline every time expression. Include explicit markers such as last week and implied boundaries such as before she moved.
- Name the reference point. Is the sentence looking from now, or reporting from a finished past timeline?
- Decide whether the period is open. Words such as today can describe an open or closed window depending on context.
- Test the intended endpoint. Does a state continue now, or did it end before another past event?
- Read each clause separately. A dated event and a consequence continuing to now may require a justified tense change.
Manual Decision Rule
If the sentence answers When did it happen? with a finished past time, start with the simple past. If it answers What has happened up to now, and why does it matter now?, test the present perfect.
What This Guide Adds to the Tense Cluster
This page audits the boundary between a finished past reference and a present-facing one. It does not teach the earlier-past viewpoint covered by past perfect vs past perfect continuous, and it does not replace the paragraph-level shift checks in tense consistency.
The similarly named passed vs past guide is a word-choice lesson, not a tense comparison. Keeping those intents separate prevents a spelling problem, a paragraph problem, and a reference-time problem from collapsing into one generic page.
Check the Form, Then Audit the Time Window
Use the checker for surface feedback, then apply the five-step audit whenever the choice depends on an open period, continuing state, or present result.
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