If you own the LLC with a partner, who is not your spouse, you should file a partnership or S-Corp return for the LLC, depending on how the business was set up.
If the partner is your spouse, and both of you
own the business, normally you would need to file a partnership return. But, since you're married you won't need to file a partnership return if you
split your business income and expenses between you and report them as separate
businesses.
If you have a refund coming from the IRS then there is no penalty for failing to file your tax return by the deadline, even if you don't ask for an extension. The penalty for filing late is a percentage of the tax owed with the return.
I don't have enough information to advise on the filing status.
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