THE "NOT YET IN BUSINESS" TRAP Costs related to planning to go into business are not deductible -- you must actually be in business. It is better to start, even on a small scale, than to spend many nondeductible dollars on feasibility studies and advice from lawyers and accountants. These are deductible once you are in business, not before. And have some proof in case you get audited -- copies of proposals, copies of advertising, or whatever is appropriate to your particular line of business.