TurboTax lets you enter both. The DB contribution goes in the Payments to Keogh box with a selection of DB - Defined Benefit, the 401(k) elective deferral goes in the Payments to 401(k) box and the employer matching or profit-sharing contribution goes in the Employer Matching Contribution to 401(k) box. Make sure that box 14 shows with code A your Net Earnings From Self-Employment. TurboTax will determine if the 401(k) contributions exceed the permissible amount but will allow the entire DB contribution.
