2020 TurboTax's calculations on the Keogh, SEP and SIMPLE Contribution Worksheet have not yet been updated for the 2020 employee regular and catch-up contribution limits, so 2020 TurboTax's calculation of the maximum employer contribution might also be incorrect as a result. Once 2020 TurboTax has been updated to have the correct employee contribution limit, TurboTax will properly calculate the employer contribution as well as the maximum employee contribution.
Your maximum employer contribution will depend on your net profit, which for many is not known until year-end, so you probably won't need to know the maximum employer contribution until at least January anyway unless you are simply trying to make the contribution as early as possible because you anticipate gains in the market between now and then.
Also, the limit you are referring to for a self-employed individual is 20% of net earnings, not 25%. Net earnings are your net profit minus the deductible portion of self-employment taxes. There is also a different, lower limit (half of what remains of net earnings after subtracting your regular, but not catch-up, employee contributions) that might apply depending on your net profit, taken into account on TurboTax's worksheet.
