Based on your financial expertise, provide your response or viewpoint on the given financial question or topic. The response format is open.

How much total salary to allocate to defer $17,500 to 401(k)?
You're on the right track, and yes, that small difference is subject to income taxes. Do you use a payroll service? I do the same thing and use my payroll software to tweak the salary until the paycheck is just a few dollars every month (we run payroll once a month), with the rest going to the 401(k) and payroll taxes. So we're rounding up just a bit just so there's an actual paycheck with a positive number, and a bit does get withheld for fed/state income tax.  Also keep in mind you can make a company match. If your plan is a solo 401(k) with just you and your wife as the sole employees, consider the 25% match for both of you. The match is not subject to payroll taxes because it is a company expense. IRS web page: http://www.irs.gov/Retirement-Plans/One-Participant-401(k)-Plans