The best I could find is https://retirementplans.vanguard.com -> Retirement plan participants -> Manage my money -> Manage my brokerage option, which gives the split between Roth money and pretax/after-tax money. But this doesn't give the split between pretax/after-tax money.
Answer from David Dean:
- Log on to your account at http://vanguard.com and access your employer plan.
- Select "View Balance Details" under your account balance.
- Select your plan name.
- Select "Source of contribution" next to "View by."