"...you'll have until Monday, Oct. 16, to actually submit your taxes."

Question

This is from a news article.

The general deadline to file your 2022 tax returns is Tuesday, April 18. That's because Washington, D.C.'s Emancipation Day holiday falls on April 17. If you know you won't make the deadline, do yourself a favor and ask for more time.

"I can't stress this enough to people, but if you need an extension, just go ahead and file that form 4868 with the IRS," Khalfani-Cox said. "That will give you an extra six months and then you'll have until Monday, Oct. 16, to actually submit your taxes."

I wonder which of the following the clause in bold means.

1. you'll have time until Monday, Oct. 16, to actually submit your taxes.

2. you will be required to submit your taxes by Monday, Oct. 16.

I mean, can modal verb 'have to' be split?

Answer 1

No, have to cannot be split in that way. The sentence means "you have time available to you up to that date".

Obviously there is an implication that you have to submit by that date, but that is an external-world implication, not what the sentence directly says.

Compare you have until six o'clock to rest or go for a walk. It does not say that you must do those things.