Benefits of a SEP-IRA. A 401(k) is the most well-known retirement plan out there.It has the most elasticity and high contribution limits. We've created several plans to allow public employees like you to put aside money from each paycheck toward retirement. Step 1: Learn the calculation. The formula to calculate a retirement is quite simple. Learn about the 2025 contribution limits for different retirement savings plans including 401k, 457, 403b, 401a and IRAs. (Includes catch-up contributions). Pinnacle Plan Design is a third party administrator (TPA) for employer-sponsored qualified retirement plans, with a physical location in Phoenix, Arizona. Add to your Max Limit if applicable.