why did you file this claim with this many documents and modifiers?

[tufguy]

Insurance representative: why did you file this claim with this many documents and modifiers?
John: We did that to avoid any denial or issue that "might be caused" because of not doing so.

Do we need to use "might have caused" instead of "might"?

 

[emsr2d2]

Insurance representative: Why did you file this claim with this many documents and modifiers?
John: We did that to avoid any denial or issues that "might be caused" because of not doing so.

It's interesting (and frustrating) that you remembered to start John's line with a capital letter yet somehow failed to start the rep's sentence with one.
In my opinion, "because of not doing so" is barely acceptable. It's grammatical but it's not what a native speaker would say. In fact, there's no need for anything at the end. Obviously their inclusion of something is aimed at resulting in a different outcome from not including it.

Do we need to use "might have caused" instead of "might be caused"?

Your original question made no sense. If you used "might have caused" instead of "might" in the original, you'd be left with "... that might have caused be caused ...". As you can see above, I assume you wanted to know if you should use "might have caused" instead of "might be caused". The simple answer is no. The resulting sentence would be:

We did that to avoid any denial or issues that might have caused because of not doing so.

Can you see that that's not grammatical? Can you work out how to fix it?

 

[tufguy]

It's interesting (and frustrating) that you remembered to start John's line with a capital letter yet somehow failed to start the rep's sentence with one.
In my opinion, "because of not doing so" is barely acceptable. It's grammatical but it's not what a native speaker would say. In fact, there's no need for anything at the end. Obviously their inclusion of something is aimed at resulting in a different outcome from not including it.

Your original question made no sense. If you used "might have caused" instead of "might" in the original, you'd be left with "... that might have caused be caused ...". As you can see above, I assume you wanted to know if you should use "might have caused" instead of "might be caused". The simple answer is no. The resulting sentence would be:

We did that to avoid any denial or issues that might have caused because of not doing so.

Can you see that that's not grammatical? Can you work out how to fix it?

We did that so that the claim didn't deny.

Is it okay?

The simple answer is no. The resulting sentence would be:
We did that to avoid any denial or issues that might have caused because of not doing so.

I am confused about what you wanted to say here. Do we need to use "might"?

 

[Tarheel]

Well, I know that an insurance company can deny a claim, but I don't see how a claim can do any denying.

@tufguy you need to simplify. You need to write shorter, simpler sentences.

 

[emsr2d2]

We did that so that the claim didn't deny get denied.

The claim didn't deny anything. As Tarheel said, a claim can't deny something. An insurance company can deny a claim. A claim can be/get denied.

Is it okay?

No. See above.

I am confused about what you wanted to say here. Do we need to use "might"?

Your question was the problem. Look carefully - in post #1, you asked "Do we need to use "might have caused" instead of "might"?" You didn't ask "Do we need to use "might have caused" instead of "might be caused?"" Do you see the difference?