To repeat - timing is everything. Here are my thoughts on tax-related timing.
• you had or adopted a child
• you changed jobs
• your spouse started working
• you have a substantial increase or decrease in income
• you have a substantial gain from the sale of stocks or bonds
• you bought or sold a home or rental real estate
• you started, acquired, or sold a business
• you retired
• you started to receive Social Security benefits
• you made unplanned withdrawals from an IRA or pension plan
• you received an inheritance
• you received correspondence from the IRS or a state tax agency