Do I need to write a business plan if I am not planning for bank loan or investment?

This is a questions that I am asked by many starting up a business and the simple and emphatic answer is YES. The fact that a bank or investing individual or institution is a secondary consideration.

Primary focus if the business plan.

The primary and most important role of writing the business plan is to guide and direct the business owner or manger in the operation of the business. Preparing and writing the plan focuses the writer consider all the possibilities and aspects associated with their business. It forces the writer to confront and come up with solutions to any problems which the plan may highlight. It helps you to think about yourself and where you have a deficit in a certain skill and allows you to focus on these and allows you to search for training opportunities or advisers to fill this gap.

A good video on what type of business plan would suit you, by Tim Berry:

Financial advantages of doing a business plan

A monthly comparison of all known costs over time, will indicate to you the necessary sales you need to accomplish in order to match these and a make a profit. It allows you to look at this figure and assess whether it is a reasonable number, if it's not then it can cast a doubt on the validity of the adventure itself. So it is not just a tool for getting an investment or working capital but it's a tool to give your business direction and assess the validity of your hypothesises.

The business plan is an important and working management tool, which allows the manager to anticipate and compensate for situations before they arise and prevent business emergencies.

Foresight and planning are a vital part of starting your own business, don't underestimate them. You can find more information on writing business plans for small business.