Which tense to use for a specific date

Question

When a specific date is used as subject or object (instead of time adverbial), should I use present tense, or tense based on the date, or tense based on other context?

For example,

1. Today is 4/17. 4/7 ____ 10 days ago.

2. Today is 4/17. 4/27 ____ 10 days ahead.

I am under an impression that 'was' is correct for #1, but for #2 'will be' sounds strange to me.

When the date is used as the object, it is even more confusing to me:

3. The deadline ____ 4/7, which ____ 10 days ago.

4. The deadline ____ 4/27, which ____ 10 days ahead.

Again I have a feeling that for #3 I should use 'was' because the subject (the deadline) is something happened in the past, however, for #4 using 'will be' suggests the deadline is not yet finalized at the time the statement was made.

Enlighten me please!

Answer 1

Your instincts are exactly right. English does not have a true future tense, and there are many cases where a past-time statement requires the past tense but an analogous future-time statement uses the present tense. For your examples, I would write:

1. Today is 4/17. 4/7 was 10 days ago.
2. Today is 4/17. 4/27 is 10 days from now.
3. The deadline was 4/7, which was 10 days ago.
4. The deadline is 4/27, which is 10 days from now.

(Note: I've changed ahead to from now, since the latter sounds more natural to me. Ahead is not wrong, but it's a bit literary, and it clashes a bit with the bureaucratic and prosaic context here.)

[…] however, for #4 using 'will be' suggests the deadline is not yet finalized at the time the statement was made.

Right — or perhaps that the deadline has been finalized, but has not yet been announced, or is only now being announced. It's not a normal way to refer to a previously-announced deadline.

Answer 2

"Will be" isn't correct for these sentences. "Is" is the appropriate term since the "10 days ahead" isn't something that will be true in the future (which is when you'd use "will be"). It's something that's true now.

2. Today is 4/17. 4/27 is 10 days ahead.
3. The deadline is 4/27, which is 10 days ahead.

For #4, you mentioned that "will be" suggests the deadline is not yet finalized at the time the statement was made. That's true. Use "will be" if that deadline hasn't been finalized.