If you arrive late for any minyan (except ma'ariv) that is about to start the amida, try to finish saying your amida before the leader gets to kedusha, if you can.
If you know you will not be able to finish your amida in time to say kedusha with the minyan:

• Wait for the leader to start the repetition of the amida.
• Say the repetition of the amida word for word with the leader, including kedusha, until the end of the third blessing (ha'el ha'kadosh).
• Once you and he have both finished saying the third blessing, you may continue at your own pace regardless of whether you will finish before or after him.

If for any reason you have not yet finished saying your amida by the time the leader begins saying the reader's repetition, do not say amen or any other replies to the prayer leader's repetition. However, when he begins to say kedusha or kaddish:

• Pause in your own amida and listen without answering or saying anything.
• Once the leader has finished kedusha (that is, he has said baruch kevod adonai mi'mkomo) or kaddish (that is, he has said da'amiran be'alma v'imru amen), resume your private amida.