As a self-employed solo professional contributing max to my SEP IRA, I want to roll over my 2003 SEP contribution into a Roth (and pay tax on the conversion amount).

While I know this is possible to do, I want to doublecheck that there are no restrictions on relative timing of the original conversion and rolling it over, that would fall in the same year under my proposed scenario.

Thank you for your advice,

Yes. Once the SEP contribution is made to the IRA, it immediately assumes the identity (or is) traditional IRA assets. There is no time limit on converting these amounts. You may convert the amount providing you meet the eligibility requirements, i.e. MAGI of not more than $100,000 and you are not filing as ‘married filing separately’