Pass-through entities (sole proprietors, single-member LLCs, partnerships)
Employer profit-sharing contributions are deducted on your business return, typically Schedule C (Form 1040), Line 19, labeled "Pension and profit-sharing plans."
Employee salary deferral contributions for self-employed individuals are deducted on Schedule 1 (Form 1040), Line 16, as an adjustment to income. This reduces your taxable income at the individual level.
Both deductions ultimately flow through to your personal return. Your tax software or CPA will handle the sequencing.
Corporate environments (S corporations, C corporations)
Employee salary deferrals are excluded from Box 1 of your W-2. They reduce your taxable wages at the payroll level rather than appearing as a separate line item on the corporate return.
Employer profit-sharing contributions are deducted as a business expense on the corporate return, Form 1120-S for S corporations or Form 1120 for C corporations.
Roth contributions
Roth contributions to your Solo 401(k) are made with after-tax dollars and are not deductible. There is no deduction to report. You will want to track Roth contributions separately in your plan records to document the tax basis of your Roth sub-account.
Form 5500-EZ
If your Solo 401(k) plan assets exceed $250,000 at any time during the plan year, you are required to file Form 5500-EZ. Total contributions for the year (both employee and employer) are reported on this form. Keeping clear contribution records throughout the year makes this filing straightforward.
Frequently Asked Questions
Do I need to report my Solo 401(k) contributions to the IRS separately from my tax return?
No. Contributions are reported as part of your regular business and personal tax filings. There is no standalone contribution reporting form outside of Form 5500-EZ, which is an informational return required only when plan assets exceed $250,000.
Are rollover contributions reported on my tax return?
The rollover itself is reported on your personal tax return as a non-taxable event, based on the Form 1099-R you receive from the releasing institution. The Solo 401(k) plan has no obligation to file separately with the IRS to confirm receipt of the rollover.
What records should I keep to support my contribution deductions?
Keep documentation of each contribution: the date, amount, contribution type (employee deferral or employer profit-sharing), and participant account. Your Self-Directed Plans plan documents include recordkeeping forms for this purpose. These records support your tax deductions and simplify Form 5500-EZ preparation if filing is required.