Fidelity is doing exactly as the should and are correct not to modify your Form 5498. The IRS requires that the SEP-IRA custodian record SEP contributions differently than regular personal IRA contributions. The custodian is required to report SEP contributions as having been made in a particular year, not for a particular year. It's your responsibility, not the custodian's responsibility, to track the year for which the SEP contribution was made and to report it correctly on your tax return.
SEP contributions must be entered into TurboTax in the business section. They must not be entered anywhere under Deductions & Credtis.
