present simple and past simple

Question

What does this sentence mean?I mean why present and past simple

I know I did not have to tell you how good this record is.

That sentence seems strange to me. What is the difference with

I know I don't have to tell you you how good this record is.

Answer 1

I know I did not have to tell you how good this record is.

In that case, you told the other person that the record was good, in the past. And in the present you tell him that you know you did not have to tell him that.

I know I don't have to tell you you how good this record is.

In that case, you don't tell the other person how good the record is, because you know that you don't have to. Both "I know" and "I don't have to" happen at the present.

The difference is that in the first sentence, you told the other person how good the record is, and it the second sentence, you don't.

Answer 2

If the words had actually been, or were, spoken, they would have been something like "This record is very good".

When we report these words, and introduce the reported statement with a past-tense reporting verb, then it is correct to backshift: I know I did not have to tell you how good this record was.

However, if the speaker considers that the record is still good at the time of reporting, then backshifting is optional (Swan, Practical English Usage [2005.278-9]. The original sentence is also correct: I know I did not have to tell you how good this record is.