Under the original Safe Harbor rules, the only short planning year allowed for Safe Harbor plans was the first year of planning. If an employers` organization lasted no less than three months, the first year of planning had to last at least three months. The Final Regulations added additional opportunities to use a short plan year (a planned year of less than 12 months) for Safe Harbor plans. A: These Solo 401k & Company 401k plans are exclusively offered by 401kBrokers.com and managed by our 100% 401kAdministrators.com subsidiary. You can invest in thousands of investment funds, stocks, bonds and options and even, if you wish, borrow from your account.