More formal would be: "Please inform me when (or 'if' should there be an implied sense of uncertainty) you've received it."

Just run-of-the-mill would be: "Let me know when (again, 'if' is possible depending on context) you get it."

"when you've received it"?


Thanks

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'when'- wenn Du es erhalten hast, oder sobald Du es erhalten hast
'if' - ob es angekommen ist

Do you mean why it's 'have received' rather than just 'receive'? If so, then I have to admit that it's largely based on feeling. I would explain it like this, though:

The present perfect--in English, at least--is used to denote an event between some point in the past and the present that cannot be specifically defined (e.g., "I received it at 11:12pm). And, in your example, the past event would be the sending of whatever it is and the present would be the actual 'Bescheid sagen', which would mean that you received the thing at some undefinable point between the two.

That's how I would explain it. Maybe someone has a better idea, though.

I think that both versions (have received/receive) are fine, but denote slightly different circumstances. The present tense form, "when you receive it", indicates that the person is quite sure it will arrive and be received. It also implies a sense of urgency in requesting the response from the other person (more like "as soon as you receive it"). On the other hand, "when you have received it" is requesting the confirmation at some point after receipt of the item (with less urgency).

@Charlie (US): The present perfect is also used when the actions in the past have consequences for/are relevant to the present (in this case, "having received" the item is important in the present), e.g. "Now that I have received word from my parents, I can go ahead with the purchase". You cannot therefore say "Please inform me when you received it".