How do I teach my teenager to manage money before they leave for college?

Give teens real responsibility with guardrails. Open a teen checking account with a debit card and have them manage a monthly budget for their own discretionary spending like clothes, entertainment, and gas, so they practice tradeoffs while you are still around to coach. Walk through a real paycheck so they understand taxes and take-home pay. Explain how credit cards and interest work, and warn about minimum-payment traps and buy-now-pay-later. If your teen earns income, help them open a custodial Roth IRA, which the IRS allows for anyone with earned income, to show compounding firsthand. Cover the basics of avoiding scams targeting young people online. Practicing these skills before college dramatically lowers the odds of costly mistakes with student loans and first credit cards.