Self-Employment Tax. This form is used by individual taxpayers who had net earnings from self-employment of $400 or more and who are likely to be liable to the IRS for self-employment tax. A taxpayer is considered self-employed for this purpose if they are an independent contractor, a sole proprietor, a member of a partnership, or are otherwise in business for themselves. If a taxpayer had a small profit or net loss from their business but wanted to pay into the Social Security system, they could use this form, Schedule SE.