I am starting a 1 person homebased business.....?

Do I still need a business plan? I will never grow larger than 1 person nor will I seek outside financing from any individuals or financial institutions

All businesses should have a business plan. It doesn't have to be long and involved but it is handy for keeping the business on track and helping you measure how well you're doing a few years from now.

Make it a simple outline. These questions will get you started. Add others as you think of them. The idea is to write an idea of what you expect to happen (the plan) so you can look back a year from now to see how close you were. You use that to write expectations for the next year.

What will the business sell?
What is the estimated cost of goods sold?
How will you determine price?
What sales volume do you expect?
What profit (% or $) do you expect to make?
Who or what is the competition?
How long are you willing to go without a profit?
What happens if your business takes off?
How much time are you willing to devote to the business?
What support will you need from your spouse?
What support can you expect?
Will you have any liabilities from the business?
What are the tax consequences, Federal and State?

You will if you need funding. The bank would want to take a look at what your plans are.

Other than that, you might want to write out your goals so you can keep tabs on your progress.

Business plans are generally for financing purposes, but it's still a good idea to lay out your goals and expectations (of yourself) in writing. It also helps to see what your expenditures are, all lined up (promotions, upkeep of supplies, maintenance on machines, etc.)