Disclaimer: I am not an accountant and I am definitely not your accountant.

Heads up that you can only contribute 20% of your earnings up (up to the limit) to a SEP-IRA. This is because you can contribute up to 25% of your taxable income, but your contributions are deducted from your income.

For example, if you make $1, and put $0.20 in your SEP-IRA, your taxable income is $1 - $0.20 = $0.80, so the $0.20 you put in is the full 25% of your income.

To contribute $55K in 2018, you will need to generate $275K of income.