Spreading the $60,000 of income helps in two ways. You don't have to come up with the money for the tax on the entire $60,000 in the year that you have the unexpected expense that necessitated the $60,000, instead giving you three years to cover the overall tax liability, and by not having to include the entire $60,000 in a single year it's likely that less of it (if any) will fall in a higher tax bracket, resulting in less overall tax liability on the $60,000.
