Learn Hardcore Malay: Malam tadi, saya mengisi borang permintaan di rumah. - Last night, I filled in the request form at home.

Malay verbs don’t change form for tense. The time reference usually comes from time expressions like malam tadi (last night) or from context.

In Malam tadi, saya mengisi borang permintaan di rumah, the phrase malam tadi tells us the action happened in the past, so mengisi is understood as filled in, not fill in.
If you changed the time phrase, the same verb form would work:

Sekarang, saya mengisi borang permintaan di rumah. → Now, I am filling in a request form at home.
Esok, saya akan mengisi borang permintaan di rumah. → Tomorrow, I will fill in a request form at home.

What is the difference between malam tadi and semalam? Can I use either one?

Both malam tadi and semalam can often be translated as last night, but they are not always identical:

malam tadi literally: last night (the night that just passed)
semalam literally: yesterday (but in everyday speech it often focuses on last night too)

In many casual contexts, they’re interchangeable when you mean last night:

Malam tadi saya tidur awal.
Semalam saya tidur awal.

However, semalam can sometimes cover more of yesterday in general, not just the night. Malam tadi is specifically the night.

Why is there a comma after Malam tadi? Is it required?

The comma separates the time adverbial (Malam tadi) from the main clause. It’s similar to English:

Last night, I filled in a request form at home.

In Malay, putting a time expression at the beginning is very common, and using a comma after it is good, clear writing, especially in formal text. In casual writing, some people may omit the comma, but Malam tadi, saya… is the standard, clear way to punctuate it.

What is the difference between isi and mengisi?

Isi is the root word and can be:

a noun: isi = contents, filling
a verb (especially in more casual/imperative use): Isi borang ini. = Fill in this form.

Mengisi is the meN- verb form that clearly marks it as a transitive verb (takes an object):

Saya mengisi borang permintaan. = I filled in a request form.

You’ll often see mengisi in full sentences with a subject and object, especially in neutral or formal Malay. Isi as a bare verb is common in commands and informal speech.

What exactly does mengisi mean here? Is it like “fill” or “fill in”?

In this context, mengisi means to fill in / to fill out a form—i.e., to write the required information in the spaces.

So:

mengisi borang = to fill in a form
mengisi borang permintaan = to fill in a request form

Depending on context, mengisi can also mean to fill (something) up (e.g. a bottle, a container, a seat), but with borang (form) it specifically means fill in (by writing).

What does borang permintaan literally mean, and why is the order like that?

Borang means form (a document to be filled in).
Permintaan is a noun meaning request (from the verb minta = to ask/request).

So borang permintaan literally is form (of) request, which corresponds to English request form. Malay typically puts the main noun first and the describing noun after it, like:

borang kerja = job form
borang pendaftaran = registration form
borang permintaan = request form

What is the difference between permintaan and permohonan? Could I say borang permohonan?

Both are nouns related to asking/requesting, but with slightly different nuances:

permintaan: from minta (to ask, request). It’s a request, demand, or order (quite general).
permohonan: from mohon (to apply, petition). It’s more like an application, formal request, petition.

Whether borang permintaan or borang permohonan is used depends on the context and the institution:

borang permintaan might be used for simpler, everyday requests (requesting items, services, changes).
borang permohonan is very common for more formal applications (scholarships, jobs, permits, etc.).

So yes, borang permohonan is also correct Malay, but it may imply a more formal/application-type request, depending on context.

Why is it di rumah and not di rumah saya? Does di rumah mean “at my house”?

Di rumah literally just means at home / at the house. Malay often doesn’t state the possessor if it’s obvious from context.

In Malam tadi, saya mengisi borang permintaan di rumah, it’s naturally understood as at home / at my house, because saya is the subject:

Saying di rumah saya = at my house is also correct, just a bit more explicit.
If you wanted to emphasize someone else’s home, you’d specify: di rumah kawan saya (at my friend’s house).

Can I change the word order, like: Saya mengisi borang permintaan di rumah malam tadi? Is that still correct?

Yes, that word order is also correct and natural:

Saya mengisi borang permintaan di rumah malam tadi.

Malay word order is fairly flexible for time and place phrases. Common options include:

Malam tadi, saya mengisi borang permintaan di rumah.
Saya mengisi borang permintaan di rumah malam tadi.
Di rumah, saya mengisi borang permintaan malam tadi. (also possible, but slightly different emphasis)

They all mean essentially the same thing; moving malam tadi or di rumah changes the emphasis slightly but not the core meaning.

Can I drop saya and just say Malam tadi, mengisi borang permintaan di rumah?

In standard Malay, you normally keep the subject pronoun, so Malam tadi, saya mengisi borang permintaan di rumah is the proper form.

In very casual spoken Malay, especially in certain dialects, speakers sometimes drop the subject if it’s clear from context, but in writing or in careful speech you should keep saya. Without saya, the sentence feels incomplete or overly colloquial.

Why is the preposition di used here? When do I use di instead of ke?

Di is used for location (where something is), while ke is used for direction (movement to somewhere).

In this sentence:

di rumah = at home (location; where the action happened)

Compare:

Saya berada di rumah. = I am at home.
Saya pergi ke rumah. = I go to the house/home.

So you use di when talking about being in/on/at a place, and ke when talking about going to that place.