Filing Form 7004 if an LLC's only members are husband and wife
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.
"I expect the company wanted to pay you for a product (on a purchase order) rather than as  a contract laborer. Whatever. Would they be willing to re-issue the check to you as a sole proprietor of a business named ABC Consulting (or anything like that)? You can register your sole proprietor business with the state using a ""Doing Business As"" (DBA, or fictitious name), and then open the bank account for your business using the check provided by the customer as the first deposit. (There is likely a smaller registration fee for the DBA.) If they won't re-issue the check and you have to go the LLC route... Scrounge up $125 doing odd jobs or borrowing from a friend or parents. Seriously, anyone can earn that amount of money in a week or two. Besides the filing fee for the LLC, your bank may require you to provide an Operating Agreement (which is not required by the State). The Operating Agreement can be simple, or more complex if you have a partner (even if it's a spouse). If you do have a partner, it is essential to have such an agreement because it would specify the responsibilities and benefits allocated to each partner, particularly in the event of equity distributions (taking money out of the business, or liquidating and ending the LLC). There are websites that will provide you a boilerplate form for Operating Agreements. But if your business is anything more than just single member LLC, you should pay an attorney to draw one up for you so the wording is right. It's a safeguard against potential future lawsuits. And, while we're at it, don't forget to obtain a EIN (equivalent to a SSN) from the IRS for your LLC. There's no cost, but you'll have to have it to file taxes as a business for every year the LLC exists and has income. Good luck!" According to the Illinois Department of Revenue, you don't have to file any taxes that are specific to a LLC, only your personal taxes. LLC on Federal level is disregarded, instead you submit all your business income/expenses on Schedule C. On the state level - it seems to be the same (only individual tax return). Consult your state certified tax specialist. That is not the case in other states, for example in California LLC has to file its own tax return and pay its own taxes, in additional to the individual taxes. An LLC does not pay taxes on profits. As regards tax a LLC is treated as a Partnership, but instead of partners they are called members. The LLC is a passthrough entity. As in Partnerships members can have a different percentage ownership to the share of profits. The LLC reports the share of the profits of the members. Then the members pay the tax as an individual. The profit of the LLC is deemed to have been transferred to the members regardless of any funds transferred. This is often the case as the LLC may need to retain the profits for use in the business. Late paying customers may mean there is less cash in the LLC than is available to distribute.  The first answer is wrong, only a C corporation files a tax return. All other corporate structures are passthrough entities. The C corporation pays corporation tax and is not required to pass any funds to the shareholders. If the C corporation passes funds to the shareholders this is a dividend, and taxable to the shareholder, hence double taxation. Yes, of course. Your business is active since it was established, it just didn't do anything. This is of course re the State taxes, the IRS considers LLC as a disregarded entity and it flows directly to your Schedule C if you're a single member, or your 1065 if you're multiple members. State of Texas never considers LLC as a disregarded (See here questions 13 and 14). You may not pay any taxes, but you have to file. No they do not. From form 1040 instructions, a single, non-blind dependent under age 65 must file if the following are true: You must file a return if any of the following apply.  There is no return required for receipt of a gift. Since from the question it seems that you're talking about the US taxation, I'll assume that. You can definitely continue filing jointly. Being members of a partnership has no bearing on how you file your own tax return. The partnership will distribute K-1 to each of you separately, but you'll report both of them on the same return. "Square use SSN to verify identity, and they only ask for the last 4 digits for that purpose. If she entered the full SSN - then she entered it into the tax id field, which was a wrong thing to do. It is also worth mentioning that since you mentioned a ""business partner"" that ""should have taken care of taxes"" that you should have a tax adviser whose job would be to take care of taxes and ensure that your interests are well-represented. I would suggest not to try interacting with the IRS on your own. Hire a tax adviser (EA/CPA licensed in your State) to do that. That tax adviser will be able to fix the problem (there are different ways of doing it, depending on the circumstances) and also verify that the business taxes were properly taken care of. When dealing with business partners - assume that what they've ""supposedly"" did was not done, until you see it with your own eyes. Saying that ""Supposedly, her business partner took care of all tax issues"" means, in this case, that you've been caught with unreported income that you tried to conceal. It is your (your sister's...) responsibility to prove otherwise. It is a very weak defense when the IRS comes knocking on the door for their money." "First, filing status. If you and your wife are legally married, you should be filing your tax returns as married, either jointly or separately. In the US, ""head of household"" has a specific meaning and is for unmarried people who are supporting one or more relatives, per the IRS. If you are working full-time and your wife is not, then likely you will file a joint return, including all your income and all the expenses for your wife's business. So yes, the losses in her business will offset your income. Depending on how complex things are, you may want to hire a professional to help with your taxes. The rules for what can and cannot be deducted as a business expense can be opaque."