sentence construction - mixed tenses/tenses agreement

1. Would it be okay if I called you when I got back home?



2. Would it be okay if I called you when I get back home?

Are both the above sentences grammatically correct? I'm still kinda confused with the tenses agreement thing. And how backshifting works. What i don't get is,do i have to convert the entire sentence to the past,or do i have convert certain parts of the sentence to the past. Or whether i should keep a sentence where i have past tense strictly to the past.

Like:

1. I was walking down the street the other day, and it hit me how the world worked.


2. I was walking down the street the other day, and it hit me how the world works.

Do I keep the sentence to the past? Or do I mix tenses?

Answer

It's worth remembering that morphologically, English only has two tenses (present, and "not-present").

By morphological I mean that verbs themselves are only modified for tense by adding -ed to make "non-present" (there's ing to make "continuous", but that's an aspect, not a tense). For all other "tense" differences, we need auxiliary verbs (be, have and things like will, would, should, could).

Probably because of that, we're quite happy to use got in the first example (it's a hypothetical/future situation, where got actually implies "not-present" rather than "past"). In the second example, past tense worked simply echoes the past tense struck me.

Note that present tense is also fine in both cases.