Use of commas before "that"

Question

I am not sure if and in which cases I have to use a comma before "that". Consider the following examples:

The first point is, that [...]

One major problem about financial returns is, that they are [...]

In [...] one can see, that both tails are heavier.

The model implies, that the returns insist of a [...]

I am not sure about the commas in this context.

This has little to do with your question, but, whenever I see myself using the verb is that way in writing, I try to restructure the sentence. So, instead of: One major problem about financial returns is that they are X, I might write: X is a major problem with financial returns. Also, instead of: The first point is that both tails are heavier, it would get shortened to: First, both tails are heavier. Sentences usually read much better after such editing. — J.R., Aug 18 '13 at 09:21

score 6 · Answer 1 · answered Feb 12 '15 at 02:00

None of the examples you gave require a comma. As a rule of thumb, you don't use a comma before a clause that begins with that.

You're veering to the territory of restrictive and nonrestrictive clauses. A restrictive clause limits the meaning of a sentence when you remove it. A nonrestrictive clause doesn't. Here are two examples (forgive the passive voice):

Restrictive: The rules of grammar that are obsolete should be ignored. Just the crusty old ones that I don't agree with.

Nonrestrictive: The rules of grammar, which are obsolete, should be ignored. Yes, all of them!

As you can see, they are very different sentences.

I think that, that being the case, we should tread warily. – Edwin Ashworth Aug 28 '19 at 15:01 — Edwin Ashworth, Aug 28 '19 at 15:01

score 5 · Answer 2 · answered Aug 18 '13 at 08:58

Personally, I would remove all of them.

In general, that is not introduced by a comma, as this would separate the two sentences which that (conjunction) links.

Besides, when you use that as a relative pronoun, you cannot use it in non defining sentences (where you use which), but these are the only ones where a comma is needed, to separate them from the main clause.

Summing up, all the sentences you have provided can do without commas before "that".

Use of commas before "that"

2 Answers2

Linked