If you are a sole proprietor, the contribution limits are confusing in your situation because your total earned income will be over the social security wage base for 2017 ($127,200). However, the general rule is that the maximum contribution for a sole proprietor is 20% of net profit reduced by half self-employment tax (The 25% limit applies to employees, and many people mistakenly use that, instead of 20%). If you were under the wage base, the maximum contribution you can make is approximately 18.59% of your net profit. It may be slightly more than that in your case.
See IRS Publication 590 for worksheets to calculate your maximum SEP-IRA contribution.
