I'd say: "Waar was je?" or "Waar zat je?" with proper intonation. Adding "nou" to the end makes the question somewhat more "pressing", which can be appropriate at times. It can suitable for when you're annoyed when someone is late, or when you have been worried about him or her. Translation of "I've been waiting on you, and you're late." is interesting as well, because the literal translation "Ik was/zat op je te wachten, en je bent te laat." doesn't sound right to me. I don't think we often say: "je bent laat" in Dutch. It might be too blunt? (strange knowing the Dutch reputation for being blunt) I think we rather point out other things that imply the other is late: i.e. "We hadden een afspraak". We do say: "Sorry dat ik laat ben." though.

It does sound like asking what places she has visited. There are several options. to ask where a person has been because he/she is late is: - Waar kom je nou vandaan? --> Where are you coming from? - Waar heb je nou gezeten? --> Litt: Where have you been sitting? - Waar was je nou? --> Where were you? - Waar zat je nou? --> Litt: Where were you sitting? - Waar zat je nou al die tijd? --> Litt: Where were you sitting at the time. As you can see I added "nou". The pronounciation is similar to the English "now" but has a different meaning. People often use it to indicate impatience. " Nou" often (not always) has a negative expression.

In addition to the previous answers if you want to use "laat" to express that a person is really late you can also simply say: "Wat ben je laat." The "wat" is the sentence is not a question but as simple way to emphasize something. In English you could use "how". For example: - wat aardig --> how nice.

Mostly I agree with the other answers. However, I wanted to translate your sentence (since that wasn't done) "Where have you been? I've been waiting on you, and you are late," I would translate as: "Waar was je nou? Ik zit hier maar te wachten en dan kom je nu pas aanzetten." (Where were you? I've been waiting since forever and you only show up now) As Merijn pointed out, in Dutch you don't really say "Je bent laat" ("you're late"), although you do say "je bent te laat ("you're too late"). I believe most commonly people point out either the time they were expecting you, or the amount of time you're late: "ik verwachte je om 8 uur" (I expected you at 8), "ik verwachte je een half uur geleden" (I expected you a half hour ago).