Used to or past simple with the adverb 'When'

Question

I know that both 'Used to' and past simple can be used to talk about things that happened in the past, and that 'Used to' is informal in negative sentences but is the preferred construction when the sentence is positive.

The main function of 'Used to' is expressing a habit that you had in the past, but no longer have in the present. Past simple can be used to the same effect but isn't as clear, as the present situation is unknown.

However, if the sentence already suggests that the situation has changed with past simple, is using 'Used to' still necessary, or even grammatical?

For example, which of the sentences below is correct or more formal?

1. (Back) When I worked as a teller, I had a decent income.

2. (Back) When I used to work as a teller, I had a decent income.

I was able to find some examples of the type of construction sentence number 2 uses with advanced book search, but there is an air of tautology around it that is hard to put into words.

In short, which (if not both) sentence is the correct version, and why? Or can both of them be used interchangeably?

Another example

1. When I went there, I was the top student.

Or

2. When I used to go there, I was the top student.

Many thanks.

Answer 1

We don't use When I used to + VERB-PHRASE when the verb-phrase refers to an occupation or to a role or to a position or to any persistent state. With when I used to, the verb-phrase must refer to something we did from time to time or on occasion.

When I used to be... ^{ungrammatical}

When I was ... ^grammatical

When I used to dig for clams ... ^grammatical

When I used to be a clam-digger... ^{ungrammatical}

When I was president of the club...

When I used to be president of the club... ^{ungrammatical}

When I worked as a teller... ^grammatical

When I used to work as a teller ... ^{ungrammatical if referring to an occupation you had for a contiguous period of time}

When I went there, I was the top student. ^grammatical

When I used to go there ... ^{ungrammatical when the meaning of "go there" is "attend as an enrolled student"}

Answer 2

I had the trouble of understanding this myself a very long time ago then I found an article in LearnEnglish at https://learnenglish.britishcouncil.org.

The article Past habit – used to/would/past simple says that:

When we talk about things that happened in the past but don’t happen anymore we can do it in different ways. we can use "used to", "would" or the Past Simple.

1. We can use ‘used to’ to talk about past states or repeated past actions:
   • We used to live in New York when I was a kid.
   • I used to smoke but I gave up a few years ago.

Remember that ‘used to’ is only for past states/actions that don’t happen now – we can’t use it for things that still happen now.

2. We can use ‘would’ to talk about repeated past actions, however, we can't use it speak about past states.
   • My teachers would always say “Sit down and shut up!”
   • We would live in New York when I was a kid. (Incorrect)

Often either ‘would’ or ‘used to’ is possible. Both of these sentences are possible:

• Every Saturday, I would go on a long bike ride.
• Every Saturday I used to go on a long bike ride.

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3. We can use the past simple in the same way as ‘used to’ and ‘would’ to talk about repeated past actions. We can also use the past simple for past states.
   • We went to the same beach every summer.
   • I went to Egypt in 1988.

However, if something happened only once we can’t use ‘used to’ or ‘would’ – we must use the past simple.

Based on what the British Council tells us, "When I worked as a teller, I had a decent income." and "When I used to work as a teller, I had a decent income.", and even "When I would work as a teller, I had a decent income." all mean the same thing; a repeating action in the past.

However, "When I went there, I was the top student." - we can use "when" with Past simple only to speak about past habits and states. So this sound awkward. It can mean two different things:

• Each time (whenever) I went there, I was the top student. (Meaning you already were a top student whenever you went there).
• Once, when I went there, I was the top student. (Only one time in the past when you went there, you already were a top student)

The second sentence "When I used to go there, I was the top student." means only one thing:

• Whenever I went there in the past, I was the top student. (Now again, you already were a top student whenever you went there)

I doubt that Past habits are possible in if-clauses but they are possible in when clauses and even in while clauses. Compare:

• I could never understand harmony when I used to play guitar. (He doesn't play guitar anymore, but when he had the habit of playing it he couldn't understand harmony. He may be playing another instrument now)
• When I used to play guitar, I could never understand harmony.

And with a while clause:

• It wasn't easy to throw up playing football due to the trauma while I used to do it everyday. (At the time when I used to play football everyday it was hard to throw up doing it)

I also wish to notice that "used to" and Past Simple mostly focus on the habit, not its duration or frequency unlike "would", which expresses that an activity was routine, typical behavior, having duration or frequently repeated.

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There are few notes on how to use "used to", "would", and Past Simple:

1. Use "would" for a custom. Use "used to" for a discontinued habit.
   • In the past, people used to call a person on his or her birthday. (Incorrect)
   • In the past, people would call a person on his/ her/ their birthday. (Correct)
2. Don't use an adverb of time with "used to". Either remove the adverb, change the verb to past tense when using an adverb for time or use a time-relative clause to refer to an earlier stage of life.
   • Last year, I used to study very hard. (Incorrect)
   • Last year, I studied very hard. (Correct)
   • I used to study very hard. (Correct)
   • When I was in college, I used to study very hard. (Correct)
3. "Used to" is not used with a quantity of time. Use past tense with a quantity of time.
   • I used to live in San Diego for five years. (Incorrect)
   • I used to live in San Diego. (Correct)
   • I lived in San Diego for five years. (Correct)
4. Don't use a repeated adverb of time, use the past tense or an adverb of frequency instead.
   • I used to go to the gym several times. (Incorrect)
   • I went to the gym several times. (Correct)
   • I often used to go to the gym. (Correct)

Answer 3

I think first example is more formal. This is more of a theoretical question, and so the answer depends a lot on what framework you prefer. "Used to" in this context is sometimes called "want to", "ought to" and so on. I'm pretty sure "used to" is a set idiomatic phrase that marks verbs as being in the imperfect (past continuous) tense.

Read this: English Quasi-Modal Verbs

Answer 4

"Used to" provides emphasis that:

• something was a habit
• something is no longer true

"When" is used to:

• Describe a specific time of an event / a state (When John died.../When water boils)
• Join the timing of events / states / things that happened concurrently

Generally speaking, it is more acceptable to say "When I did X" instead of "When I used to do X". Remember, "when" is trying to either specify a time of an event / state, or to join the timeline of two events / states. "I used to do X" is not a specific event / state - it is a sentence of its own. On the contrary, "I did X" is very specific event / state.

"When" and "used to" can only be used together generally when "used to" is not used to describe time. Example - "A bottle was used to hold the water collected by the team"

A special note is that "Back when I used to" is a special phrase. It is acceptable to use this phrase even when "When I used to" is not strictly correct.