Yes, if they meet certain requirements. A SEP-IRA is considered a retirement plan, so the Adjusted Gross Income (AGI) limitations have to be considered. If your AGI, which is computed after the SEP contribution, is in excess of those limits, then the IRA contribution that you make would be nondeductible. The information on the AGI limits is in Publication 590, Individual Retirement Arrangements (IRAs) , in the section How Much Can I Deduct? Your SEP IRA Contribution and Traditional IRA Contribution may both be made to your SEP IRA.

References:

• Publication 590, Individual Retirement Arrangements (IRAs)
• Tax Topic 451, Individual retirement arrangements (IRAs)