Aspect Markers Are Optional

In everyday spoken Vietnamese, omitting aspect markers is a standard, high-frequency pattern. Because verbs never change form, time is established by context or explicit time words (like hôm qua 'yesterday' or ngày mai 'tomorrow').

1. The "Over-marking" Trap
English speakers often feel the need to insert đã (past) and sẽ (future) into every sentence to simulate verb conjugation. While saying "Hôm qua tôi đã đi chợ" is grammatically correct, native speakers frequently just say "Hôm qua tôi đi chợ". Dropping these markers is the most natural pattern, though keeping them is sometimes done for rhythm or clarity. Note that đang (ongoing) is an exception; it is often retained to specify the continuous nature of an action, though it can easily be dropped if an explicit continuous time phrase like bây giờ (now) is present (e.g., "Bây giờ tôi ăn cơm").

2. When are they used?
You will often see đã and sẽ in formal writing, news broadcasts, or when a speaker wants to add emphasis (e.g., confirming an action definitely happened or will happen). In casual speech, they are frequently dropped. However, other common time markers like vừa / mới (just did) and sắp (about to) are generally retained, because dropping them would completely change the meaning of the sentence by losing their highly specific aspectual meanings.

3. Bare Verbs are Tenseless
Don't confuse a bare Vietnamese verb with the English present tense. A sentence like "Tôi ăn cơm" can mean "I eat" (habitual), "I ate," or "I will eat," depending entirely on the context. However, expressing an ongoing action ("I am eating") often requires keeping the marker đang.

4. Completed Actions and Negation
Instead of using đã before the verb to show past tense, native speakers usually prefer adding rồi (already) at the end of the clause (Subject + Verb + Object + rồi) to show an action is finished. Do not place it directly after the verb if there is an object (e.g., say "Tôi ăn cơm rồi", not "Tôi ăn rồi cơm"). Additionally, rồi is frequently used with adjectives or state verbs to indicate a change of state or a new situation (e.g., "Tôi đói rồi" means "I am hungry now"). (Note that dropping đã and relying entirely on rồi is a heavily Southern Vietnamese trait, whereas Northern speakers are slightly more likely to retain đã in everyday speech). For strong emphasis that a task is 100% finished, they can be used together as đã ... rồi (e.g., "Tôi đã ăn rồi"). Finally, to negate a past action, the default choice is usually chưa (not yet). Using không (not) for the past is less common and often sounds like a direct refusal or denial (e.g., "Hôm qua tôi không đi" means "I didn't go [and I chose not to]"). While đã không is sometimes used in formal contexts, learners often make the mistake of saying không đã, which is completely ungrammatical and must be avoided.