Most of the personal income tax rules that apply to individual retirement accounts, annuities, or simplified employee pensions also apply to Roth IRAs. For example--
An exclusion is allowed for payments made by employers directly to Roth IRA trustees or issuers for the benefit of employees.
No exclusion or deduction is allowed for contributions to a Roth IRA made by, on behalf of, or attributable to, an employee or self-employed person, directly or indirectly, whether through payroll deduction, a salary reduction agreement or otherwise.
Income on assets held in a Roth IRA is not taxable.
Distributions are includable in income to the extent that contributions were not previously included if made before the individual for whom the account is maintained obtains age 59 ½ or retires from service.
The cost recovery method is used to determine the portion of a distribution to be included in income.

Special rules, however, apply with respect to roll over contributions and plan conversions.

The conversion of a traditional IRA to a Roth IRA is generally not taxable.  That is, monies transferred from a traditional IRA to a Roth IRA via conversion (whether by a trustee-to-trustee transfer or a roll-over within 60 days) are generally not subject to Pennsylvania personal income tax.  However, any amounts transferred from the traditional IRA that are not put into the Roth IRA, be it by federal income tax withholding or otherwise, are subject to Pennsylvania personal income tax.  In such a situation, basis is allocated pro-rata between the taxable distribution and the non-taxable conversion.  If there is a partial rollover/conversion, the basis in the traditional IRA must be allocated pro-rata between the traditional IRA and the Roth IRA.