[sweeps]

1. I do software development as a side-gig.

2. It's a simple cash-based business and I have no expenses so I just file Schedule C-EZ.

3. I have extra taxes taken out of my primary job's paycheck to compensate for the income, so there's no need to make quarterly tax payments. An EIN is not necessary; in fact you don't even need to name your business in this situation.

4. I do my own taxes. The last few years I've used free e-filing.

5. You can, of course, claim various expenses (use of home, use of computer, travel, etc.). The rules can become complicated though, so be sure to read the instructions carefully. In my situation, the write-offs are so small it's not worth the effort nor the audit risk.

Be aware that you have to pay 13% or so in Social Security and Medicare tax (Schedule SE). However, you get to claim half of that as a deduction. Also once you hit a certain level (roughly $90,000 in income), you don't have to pay Social Security tax on anything higher (although you have to pay Medicare tax on an unlimited amount of income).

Good luck on your business!