Resolved: TurboTax was calculating the maximum because the SEP 4d box was checked on the Keogh,SEP,SIMPLE Contribution Worksheet, which overrides the actual deduction with a maximum deduction, even though this is an Individual 401(k), not a SEP.
To get the accurate deduction, be sure that the "Check here to compute the maximum deductible contribution" for SEPs is UNCHECKED.
