To answer this question requires the small business or individual to look at their needs. The most important questions to ask are:
1) Do I have the knowledge to do accounting for my business?
2) Do I have the time to complete this task at the level necessary as not to draw the IRS attention?
3) Can I complete these task by their due dates? Such as, tax deadlines or even bank deadlines.
4) Do I really want to do these daily task?
If the answer to any of the question is "no", then you most likely need professional help.
If you have never started up your own company before, seeing an accountant before you form your business is a good idea. Deciding what form of entity to create is an important decision, such as, whether you want to start a corporation, partnership, or LLC.
Accountants can address your tax and business concerns.
If you are a start up business, you will need a business plan. You will need to explain how your business plan or financial model will positively effect revenue and profits.