Failing to get the IRS's consent to an accounting method change proves costly for a businessman.  After years of reporting income and expenses on the cash method, he changed to the accural method so he could deduct $78,000 in legal fees billed to him. But, because he didn't obtain the IRS's approval before switching his accounting method, the Tax Court said he must stick to the cash method.  As a result, his write-off is limited to the $12,000 of legal costs that he paid during the year.