The decision in retirement plans types between Roth and Regular tax-deductible 403(b) plans can be more significant for ministers than it typically is for other taxpayers. 

This is due to the intersection of the Ministers Housing Allowance and the Minister's dual status with the IRS. Ministers are considered employees for income taxes but are considered self-employed for Medicare and Social Security taxes (SECA). 

The income and SECA taxes paid by a minister with a Roth plan are generally substantially higher than the taxes that would be paid with a Regular tax-deductible 403(b) plan. 30-40% higher taxes with the Roth plans are common. 

While serving in ministry, Regular, tax-deductible 403(b) plan contributions are excluded from SECA tax calculations. These contributions are also exempt from federal income tax and most state income taxes. 

Once retired, a portion of Regular plan withdrawals can be designated as housing allowance, which reduces income taxes. Retirement plan withdrawals are exempt from SECA taxes. 

A national tax group that exclusively works with ministers taxes for over 40 years has said that ministers should opt for a tax-deductible 403(b) plan when available, and that ministers should not participate in Roth plans or IRA's without tax counsel. 

This is meant to be informational only. Do not make changes to your retirement plans without first discussing matters with a tax advisor. If you have questions that I can help with (free of any obligations), let me know.