The new tax code makes a big change to the individual retirement account landscape, according to financial advisor Winnie Sun.

People are no longer allowed to go back and recharacterize their individual retirement accounts — if, for example, they realize they paid more taxes than they needed to, she said.

"This is critical, because if you are converting your traditional IRA at this point, it is permanent from 2018 and going forward," said Sun, founder of Sun Group Wealth Partners. "So make sure you understand your options and get it right the first time."

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However, she added, if you converted your IRA in 2017, you have until Oct. 15 to still make changes, she said.

One of the best features of the tax cut is that you're likely to have more disposable income, Sun said.

"You don't want to just go spend it, you want to go ahead and save it. But not just save it, put it in vehicles which really would give you more bang for your buck," Sun said.