For every change in tax law, there are scores of people who want to outrun it and beat the system. Especially when it happens with less than three weeks left in the year.

Since the final federal tax bill appeared on Friday, many people have had questions about prepaying taxes, a wide-ranging strategy that encompasses various efforts to save money by paying some taxes early. It seems counterintuitive, but sometimes, if you pay taxes in one year instead of another, you can come out ahead financially. This will depend on your income, the amount of your overall deductions and any changes in tax law.

This year, there’s a twist: The authors of the tax bill cut off one prepayment move that many people had hoped to make while leaving at least two other options open.

For people who have money available to prepay their personal taxes, here is a breakdown of the options, according to both the bill itself and staff members from the relevant House and Senate committees.