Learn English – “Upon receiving…” or “When receiving…”

word-choice

What is the proper word to use in the following sentences:

Example 1:

  • "When receiving a package, check the mailing address to ensure…"
  • "Upon receiving a package, check the mailing address to ensure…"

Example 2:

  • "Then, when receiving a package, check the mailing address to ensure…"
  • "Then, upon receiving a package, check the mailing address to ensure…"

What are the rules associated with when I should use "Upon" vs "When" in similar sentences to the example?

Best Answer

Practically-speaking 'when' and 'upon' are usually used to mean the same thing.

When you get the parcel... means, effectively, the same as On receipt of the parcel...

But they are not the same.

When (in reference to a definite actual occurrence or fact) means at the time that, on the occasion that. (OED)

Upon (often shortened to 'on') means Immediately after; following on" (OED)

So ...

The postman may ask you to sign for a parcel when it is delivered to you. You, on the other hand, upon receipt of the parcel, may phone in due course to let your friend know that their parcel has arrived.