"Individual 401(k)" and "Solo 401(k)" are two names for the same thing.
The regular elective deferral limit for 2021 is $19,500. If you were over age 50 by the end of 2021 you also have a catch-up contribution limit of $6,500. The maximum permissible total of all additions (employee and employer contributions) to your Solo 401(k) for 2021 is $58,000 plus, if over age 50, the $6,500 catch-up. Unless you simply use the Maximize function for an individual 401(k), you must enter the regular elective deferral, catch-up elective deferral and employer profit sharing contribution in separate entry boxes. Note that your employer contribution cannot exceed 20% of your net earnings, figured on a maximum of $290,000 of net earnings. Net earnings are net profit minus the deductible portion of self employment taxes. To be able to contribute a total of $61,000 you would have to be over age 50 and have at least $186,350 of net profit from self employment.
