Glossary
What is Form 1120-S?
Definition
Form 1120-S is the annual income tax return for S-Corporations. The S-Corp itself doesn't pay federal income tax — income, deductions, credits pass through to shareholders via Schedule K-1. The return is informational, but still required.
Due March 15 (one month earlier than personal 1040). Most S-Corp owners work with a CPA to prepare; DIY filing is possible but the form has more complexity than Schedule C.
Why it matters
- CPA preparation for a single-shareholder 1120-S typically runs $600–$1,500 per year — an overhead S-Corp filers sign up for when electing.
- Missing the March 15 deadline triggers a per-month, per-shareholder late-filing penalty ($220/month in 2024). Extending is easy (Form 7004); missing the deadline isn't worth it.
- The 1120-S feeds the K-1 that each shareholder reports on Schedule E of their personal return. The timing means the S-Corp return must be done before personal 1040 can be finalized.
Best practices for 1120-S
Hire a CPA for the first year
The first-year complexity (establishing accounting, reasonable salary documentation, payroll setup) is worth professional prep. Subsequent years can be simpler.
File Form 7004 for automatic extension
If you need more time, Form 7004 gets a 6-month extension (Sep 15 new due date) with no explanation required. Extension is always free.
Keep clean books year-round
A well-organized Hustlay or QuickBooks export makes 1120-S preparation dramatically cheaper. Disorganized books can double the CPA bill.
FAQ
Can I file 1120-S myself?
Technically yes using TurboTax Business or similar. In practice, most S-Corp owners work with a CPA because the reasonable-salary test, depreciation choices, and distribution tracking compound quickly.
What if I have no activity one year?
You still file a 1120-S. Zero-activity returns are common for S-Corps that were formed but not yet operating. Skipping the filing triggers penalties.
Ready for S-Corp-clean books?
Hustlay's project-tagged revenue + expense tracking exports cleanly into any CPA's S-Corp workflow. Keeps year-end prep short.