This year is going to be a happy one -- at least for some taxpayers. Among the many changes that became effective on New Year's Day are higher contribution limits for 401(k) plans, a decline in the top federal estate-tax rate and a new deduction for many people who buy mortgage insurance. The standard mileage rate rose. So did the personal exemption, income brackets and dozens of other tax items adjusted for inflation every year. While these and other changes will bring relief to millions of taxpayers, many will be hit by higher taxes. About 11 million workers will have...