"That's When" is a duet describing the aftermath of a relationship breakup, with Swift in the role of the individual who stepped away from a relationship due to needing space and Keith Urban contemplating whether he should take her back. It was originally written for Swift's sophomore album, Fearless, but was cut. In April 2021 it was one of the "From The Vault" track on Swift's re-release of Fearless.

The demo version was sung only by Swift, with notably different lyrics, and Swift in the position of needing to decide whether to take back the other person in the relationship. Swift has previously performed with Urban and opened for him on tour, and he covered her 2019 ballad "Lover."

Lyrics-

[Taylor Swift]
You said, "I know"
When I said, "I need some time, need some space
To think about all of this"
You watched me go
And I knew my
Words were hard to here
And harder to ever take back
And I said, "When can I-I-I come back?"

[Taylor Swift & Keith Urban]
And you said, "That's when
When I wake up in the morning
That's when, when it's sunny or storming
Laughing, when I'm crying
And that's when, I'll be waiting at the front gate
That's when, when I see your face
I'll let you in, and baby, that's when"
Mm, mm

[Keith Urban & Taylor Swift]
I said, "I know"
When you said, "I did you wrong
Made mistakes
And put you through all of this" (through all of this)
Then through the phone
Came all your tears
And I said, "Leave those all in our past"
And you said, "When can I-I-I come back?"

[Keith Urban & Taylor Swift]
And I said, "That's when
When I wake up in the morning
That's when, when it's sunny or storming
Laughing, when I'm crying
And that's when I'll be waiting at the front gate
That's when, when I see your face
I'll let you in, and baby, that's when"

[Taylor Swift]
And you said, "Honestly
When you were gone
Did you ever think of me?"
And I said

[Taylor Swift, with Keith Urban]
"That's when, when I woke up in the morning
That's when, it was sunny or storming
Laughing when I was crying
And that's when, you were waiting at the front gate
That's when, when I saw your face
You let me in, and baby, that's when"

That's when, when I woke up in the morning (Yeah)
That's when, when it's sunny or storming
When I'm laughing, when I'm crying
That's when it'll be waiting at the front gate
(That's when I miss you, that's when I want you)
That's when, when I see your face
That's when I love you, that's when