All SEP contributions must be made by your employer to a SEP plan established by that employer. Except for a SARSEP established before 1997, all SEP contributions are employer contributions are employer contributions. All SARSEP employee contributions must be made by payroll deduction and deposited by your employer.
Some IRA custodians allow regular personal IRA contributions to be made to an IRA that is designated as a SEP-IRA, but since contributions to a SEP-IRA are by default reported as SEP contributions it's still best to make regular personal traditional IRA contributions to a separate account to avoid confusion and incorrect reporting of the contribution on Form 5498 by the IRA custodian. Whether or not your regular personal traditional IRA contribution will be deductible will depend on whether or not you or your spouse is covered by a workplace retirement plan, your modified AGI for the purpose and your filing status.
