Since you both are members of the LLC - it is not a single-member LLC, thus you have to file the tax return on behalf of the LLC (I'm guessing you didn't elect corporate treatment, so you would be filing 1065, which is the default).

You need to file form 4868 on behalf of yourselves as individuals, and form 7004 on behalf of the LLC as the partnership.

Since the LLC is disregarded (unless you explicitly chose it not to be, which seems not to be the case) the taxes will in fact flow to your individual return(s), but the LLC will have to file the informational return on form 1065 and distribute K-1 forms to each of you.

If you need a help understanding all that and filling the forms - do talk to a professional (EA or CPA licensed in your state).

Also, revisit not sending any payment. I suggest sending $1 with the extension form even if you expect a refund.

Since you both are members of the LLC - it is not a single-member LLC, thus you have to file the tax return on behalf of the LLC (I'm guessing you didn't elect corporate treatment, so you would be filing 1065, which is the default).

You need to file form 4868 on behalf of yourselves as individuals, and form 7004 on behalf of the LLC as the partnership.

Since the LLC is disregarded (unless you explicitly chose it not to be, which seems not to be the case) the taxes will in fact flow to your individual return(s), but the LLC will have to file the informational return on form 1065 and distribute K-1 forms to each of you. So you wouldn't pay additional estimated taxes with the extension, as you don't pay any taxes with the form 1065 itself.

If you need a help understanding all that and filling the forms - do talk to a professional (EA or CPA licensed in your state).

Also, reconsider not sending any payment. I suggest sending $1 with the extension form even if you expect a refund.