No, you may not make $18k of pre-tax contributions and $18k of Roth contributions. There's a third type of contributions: traditional after-tax contributions. These contributions are similar to Roth contributions in that you pay tax on the amount contributed when you earn it, but they differ from Roth contributions because you have to pay tax on any gains when you withdraw the money. These after-tax contributions don't count toward the $18k limit. Instead they're constrained by a $53k combined limit across all additions to the account: pre-tax contributions, Roth contributions, employer matching contributions, and after-tax contributions put together must be under $53k. Not all companies allow their employees to make these contributions; it's possible that this is not an option for you.