N4
てすみません
I'm sorry for
待ち合わせの時間に遅れてすみません。
I am sorry for coming later than the arranged meeting time.
Explanation
「〜てすみません」 states the reason for an apology: you did (or did not do) something and it troubled the other person. 「返事が遅くなってすみません」 (Sorry for the late reply). To apologize for not doing something use 「〜なくてすみません」: 「昨日連絡しなくてすみませんでした」 (Sorry I didn't contact you yesterday).
Mixed up with
The negative is 「〜なくて」, never 「×〜ないですみません」: 「来られなくてすみません」 (Sorry I couldn't come).
Politeness: with friends and family 「〜てごめん」; in general 「〜てすみません」; at work or with elders 「〜て申し訳ございません」.