Self-employment tax: how it works in 2025

Summary

Sources: IRS Self-Employment Tax hub — confirm the Social Security wage base annually.

Self-employment tax combines the employee and employer shares of Social Security and Medicare on a statutory base derived from net earnings.

1. The 92.35% base

This ratio is built into law to approximate wage-worker treatment. Any educational simulator should spell it out to prevent confusion with gross accounting profit.

2. Social Security wage base

Above the cap, the Social Security portion stops stacking; Medicare continues, with possible additional Medicare tax beyond certain thresholds (not modeled in full fidelity here).

3. Deductible part of SE tax

An income-tax deduction for one-half of SE tax offsets partial double counting—see Schedule SE instructions.

4. Step table

Step	Effect
Schedule C profit	Starting point
92.35% base	Statutory adjustment
SS up to wage base	12.4% on applicable base (illustrative)
Medicare	2.9% plus possible additional tax

5. Numeric example

With $80,000 of profit and a wage base above the full Social Security portion of the SE base, Social Security tax applies on the relevant SS slice; above that, Medicare continues. Recompute with IRS-published caps and rates.

6. FAQ

Does Schedule SE replace a pro? No—classification and exemption errors happen.

7. Sources

• IRS — SE tax

8. Going deeper

Document cash vs accrual conventions, capitalized costs, and carryforward losses. Mixed-status workers (W-2 + freelance) should reconcile Social Security caps already partially used via payroll.

Bring your advisor a clean packet: general ledger, bank statements, contracts, and received 1099s—clarity reduces mistakes on the 92.35% base.