Nasa isip ko ang tirahan.

Nasa is a very common Filipino form meaning in, at, on, inside, within, depending on context.

It is historically from na sa, but learners usually just treat nasa as one common unit.

In Nasa isip ko ang tirahan, nasa isip ko literally means in my mind or on my mind.

Filipino word order is often more flexible than English, and it does not always follow subject + verb + object the way English does.

Here, the structure is closer to:

• Nasa isip ko = is in my mind / is on my mind
• ang tirahan = the residence / the place to live

So the sentence is roughly:

• The residence is on my mind
• or more naturally, I’m thinking about the residence

Filipino often puts the location or predicate first, then the ang phrase after it.

Ang marks the topic of the sentence.

In Nasa isip ko ang tirahan, the topic is ang tirahan.

That means the sentence is organized around the residence / dwelling place as the thing being talked about.

A helpful way to feel it is:

• As for the residence, it is on my mind
• The residence is what’s on my mind

Ko is the usual short possessive form meaning my in this kind of construction.

So:

• isip ko = my mind

This is the most natural everyday pattern.

You can also see forms like aking, but aking isip is more formal, poetic, or emphatic in many contexts. For normal speech, isip ko is what learners should expect most often.

Tirahan means place to live, dwelling, residence, or home depending on context.

It comes from the root tira, which can relate to staying/living somewhere, plus the suffix -han, which often forms a word for a place connected to the root.

So tirahan is literally something like:

• a place where one stays/lives

Depending on context, English translations could include:

• home
• residence
• dwelling
• place to live

It is both understandable literally and natural idiomatically.

Literally, it says:

• The residence is in my mind

But in more natural English, it usually means something like:

• The residence is on my mind
• I’m thinking about the place to live
• I have the residence/home in mind

So the Filipino wording uses a very natural “in/on my mind” idea, much like English does.

Yes. Iniisip ko ang tirahan is also correct, and it means:

• I am thinking about the residence
• I’m considering the place to live

The difference is mainly in feel:

• Nasa isip ko ang tirahan = The residence is on my mind
  This sounds more like it is occupying your thoughts.
• Iniisip ko ang tirahan = I am thinking about the residence
  This is more direct and action-oriented.

So the first is more of a state, while the second is more of an active process.

Yes. Filipino often does not need a separate word for is/are in this kind of sentence.

English requires:

• The residence is in my mind

But Filipino can simply say:

• Nasa isip ko ang tirahan

The linking idea is understood from the sentence structure itself.

Tirahan is correct and natural, but whether it sounds everyday depends on context.

In casual speech, people might also use more specific or common words like:

• bahay = house/home
• uwian in some contexts = place one goes home to
• matitirhan = place to stay/live in

So tirahan is a good general word for dwelling/place to live, but in real conversation a speaker may choose a more specific term depending on what they mean.

Because the sentence is built with a predicate-first pattern.

The part Nasa isip ko comes first and tells the state or location, and then ang tirahan identifies what that state applies to.

This is very normal in Filipino.

Compare:

• Nasa isip ko ang tirahan.
• More literally: In my mind is the residence.

That may sound unusual in English, but it is a standard Filipino pattern.

Yes, it can.

Depending on context, Nasa isip ko ang tirahan can mean not only I’m thinking about the residence, but also something like:

• I have a residence in mind
• I already have the place in mind

That interpretation becomes especially likely if the conversation is about choosing or discussing a place to live.

Context is what tells you whether it means:

1. the place is simply on your mind, or
2. you have a particular place in mind.

You generally should not remove ang here.

Ang tirahan is the marked topic phrase. Without ang, the sentence would no longer have the same clear grammatical structure.

For learners, it is best to think of ang as an important marker that helps show:

• what the sentence is about
• what noun phrase is functioning as the topic

So Nasa isip ko ang tirahan is the correct full pattern.

A very natural way to understand it is:

• The residence is on my mind
• I’m thinking about the place to live
• I have the place in mind

If you want to remember the structure, a good mental gloss is:

• nasa = in/on/at
• isip ko = my mind
• ang tirahan = the residence / dwelling

So the whole sentence is essentially:

• The residence is in/on my mind