Rep. Dave Camp (R-Mich.), chairman of the House Ways and Means Committee, is proposing slimming the advertising tax deduction. Sources say the measure, which could cost advertisers millions and reduce revenue for ad-supported media, has been written into a working draft of a tax reform bill. It would allow advertisers to deduct only 50% of all ad expenses in the first year and amortize the remaining 50% over the next 10 years.