It may seem like the wrong time of year to be thinking about taxes. Fall has only just begun, and it will be months before the IRS begins accepting 2016 income tax returns. Yet, now may be the best time to begin a review of income and expenses. With the holidays fast approaching, waiting could mean running out of both time and money to take advantage of tax-minimizing strategies.

“If you’re a W-2 earner, then there is probably not a need to look at it now,” says Charlie Harriman, a financial planner with Cloud Investments in Huntsville, Alabama. However,those with high incomes or itemized deductions, and the self-employed, may find it’s in their best interest to start working on their personal taxes sooner rather than later.

[See: How to Reduce Your Tax Bill by Saving for Retirement.]

Plan now to avoid surprises next spring. Joe O’Boyle, a certified financial planner with Voya Financial Advisors, says he tells his clients now is the time to start their tax review. “We recommend they take a proactive approach to their tax planning and meet with a CPA in the fourth quarter,” he says. After that meeting, taxpayers should have a better idea of how they will end the year financially, something that can help them avoid any unpleasant surprises.

For example, there is an income cap on who can contribute to a traditional IRA. “What we can do is jerk that money out of there,” says Scott Goble, a certified public accountant and founder of Sound Accounting in Chickamauga, Georgia. Otherwise, if the problem is overlooked before the end of the year, people could get hit with not only taxes on the contributions but penalties as well.

“All [high] wage-earners have a year in which taxes take them completely by surprise,” Harriman says. That could be because of unexpected penalties or simply because their income pushes them into a higher tax bracket. The additional taxes may be no small amount either. “My client this past year owed $25,000 in additional income taxes,” Harriman says as an example.

[See: 10 Low-Tax Places to Retire.]

Early planning means time to make changes. Beginning a tax review now means there is plenty of time for a tax professional to step in and recommend changes. “That’s the bigger problem,” Craig Wear, founder of My 401K Investing, says about waiting. “They’ve put [their CPA] in a position where there is no time to plan.”

However, knowing in October that changes need to be made gives ample opportunity to maximize deductions. Depending on income and other factors, taxpayers may be able to contribute more to a 401(k) plan, fully fund a health savings account, sell stocks at a loss or make additional charitable donations, all of which must be done before Dec. 31 to be included on a person’s 2016 tax return. “After the first of the year, the number of options drop to very, very few,” Goble says.

In the event someone’s income is lower than expected, other tax strategies may come into play. Converting a traditional IRA to a Roth IRA may mean significant tax savings in retirement but requires a person to pay income tax on the converted amount. As a result, conversions are typically best done in a year in which a person is in a lower tax bracket. “If someone wants to convert, that has to happen before December 31,” O’Boyle says.

[See: 10 Financial Perks of Getting Older.]

The self-employed may have other options. Early tax preparation may be most important for those who are self-employed. “It’s very important before the end of the year to see if the estimated tax payments they’ve made through the year are sufficient,” Goble says. Self-employed individuals can also decide whether to delay some invoices to January or incur expenses prior to the end of the year if they want to reduce their taxable income for 2016.

“Most people put it on autopilot and assume [their taxes] will be the same this year as they were last year,” Wear says. However, the tax code changes regularly, which means taxpayers should take time now to review their income and expenses before they miss savings opportunities later in the midst of the holiday rush.