At the beginning of 2010 I filed with a partner to become an "partnership" LLC with a new EIN and the works. As a returned soldier from combat, he suffered PTSD and chose not to be my partner afterall and did so shortly after we filed for the LLC. I continued throughout the remainder of the year with successful business.

My questions:

How do I file for 2010 and which forms will I use to report my taxes?
Will I need to reapply for a new EIN?

‘How do I file for 2010 and which forms will I use to report my taxes?’----> In general, you as a partner of the receive a Schedule K-1 , must report the amounts on IRS Form 1040 Schedule E; ordinary net business income or loss on 1065 SCh K-1, line 1, is reported on Schedule E and on 1040 line 17 and the amount on Sch K-1 line 14 is reported on Sch SE line 2 and on 1040 line 56( as long as the amount on Sch SE line 4 is $400 or exceeds $400, then you MUST pay SE tax, self-employment tax). Other income items are reported in the appropriate part of the 1040 tax return. For example, interest and dividends passed-through by an LLC or partnership are reported on Schedule B. Capital gains are reported on Schedule D. Estimated tax takes the place of withholding for self-employed individuals by requiring taxpayers to pay self-employment tax quarterly. In general, partners must figure their own estimated tax using the previous year's tax return and the current year's estimated profits, and make up any shortfall at the end of the year.As they are filing as partners, or self-employed individuals, they generally have to make estimated tax payments as long as they expect to owe tax of $1,000 or more when they file their returns.
“Will I need to reapply for a new EIN?”----> I guess it depends; as long as you keep your partnership as your business, you will have to obtain a new EIN if you incorporate; your partnership is taken over by one of the partners and is operated as a sole proprietorship; you end an old partnership and begin a new one.