HIGH-YIELD MUNICIPAL FUND, INVESTOR CLASS HIGH-YIELD MUNICIPAL FUND, INVESTOR CLASS, C000017685, ABHYX HIGH-YIELD MUNICIPAL FUND HIGH-YIELD MUNICIPAL FUND, S000006471 S&P Municipal Bond 50% Investment Grade/50% High Yield Index (reflects no deduction for fees, expenses or taxes) S&P Municipal Bond 50% Investment Grade/50% High Yield Index (reflects no deduction for fees, expenses or taxes) S&P National AMT-Free Municipal Bond Index (reflects no deduction for fees, expenses or taxes) SPNationalAMTFreeMunicipalBondIndexreflectsnodeductionforfeesexpensesortaxes Low Yield Risk Member Low Yield Risk Member Loss Of Tax-Exemptions Risk Member Loss Of Tax-Exemptions Risk Member S&P Intermediate Term National AMT-Free Municipal Bond Index (reflects no deduction for fees, expenses or taxes) S&P Intermediate Term National AMT-Free Municipal Bond Index (reflects no deduction for fees, expenses or taxes) HIGH-YIELD MUNICIPAL FUND, Y CLASS HIGH-YIELD MUNICIPAL FUND, Y CLASS, C000189766 HIGH-YIELD MUNICIPAL FUND, I CLASS HIGH-YIELD MUNICIPAL FUND, I CLASS, C000088012, AYMIX INTERMEDIATE-TERM TAX-FREE BOND FUND, A CLASS INTERMEDIATE-TERM TAX-FREE BOND FUND, A CLASS, C000088013, TWWOX Credit Risk1 Member Credit Risk1 Member Tax Risk Member Tax Risk Member Liquidity Risk Member Liquidity Risk Member TAX-FREE MONEY MARKET FUND, INVESTOR CLASS TAX-FREE MONEY MARKET FUND, INVESTOR CLASS, C000017692, BNTXX Municipal Securities Risk Member Municipal Securities Risk Member INTERMEDIATE-TERM TAX-FREE BOND FUND, Y CLASS INTERMEDIATE-TERM TAX-FREE BOND FUND, Y CLASS, C000189767 INTERMEDIATE-TERM TAX-FREE BOND FUND INTERMEDIATE-TERM TAX-FREE BOND FUND, S000006472 INTERMEDIATE-TERM TAX-FREE BOND FUND, INVESTOR CLASS INTERMEDIATE-TERM TAX-FREE BOND FUND, INVESTOR CLASS, C000017689, TWTIX HIGH-YIELD MUNICIPAL FUND, C CLASS HIGH-YIELD MUNICIPAL FUND, C CLASS, C000017688, AYMCX INTERMEDIATE-TERM TAX-FREE BOND FUND, I CLASS INTERMEDIATE-TERM TAX-FREE BOND FUND, I CLASS, C000017691, AXBIX Interest Rate Risk1 Member Interest Rate Risk1 Member Market Risk Member Market Risk Member AMERICAN CENTURY MUNICIPAL TRUST AMERICAN CENTURY MUNICIPAL TRUST TAX-FREE MONEY MARKET FUND TAX-FREE MONEY MARKET FUND, S000006473 HIGH-YIELD MUNICIPAL FUND, A CLASS HIGH-YIELD MUNICIPAL FUND, A CLASS, C000017686, AYMAX INTERMEDIATE-TERM TAX-FREE BOND FUND, C CLASS INTERMEDIATE-TERM TAX-FREE BOND FUND, C CLASS, C000088014, TWTCX Below Investment-Grade Securities Risk Member Below Investment-Grade Securities Risk Member