If you’re building a startup, taxes probably sit somewhere between “I’ll deal with it later” and “Oh no, the deadline is tomorrow.” We get it, you didn’t start a company to file Form 1120 or chase W-9s from contractors.
But here’s the thing: ignoring taxes costs real money. Penalties, interest, lost deductions — they all eat into your runway. And the worst part? Most of it is 100% avoidable.
This guide is for founders who want to focus on building, not bookkeeping, but still keep the IRS happy.
If you run a U.S. startup (especially a Delaware C-Corp), these are the big ones:
| Date | Form | Why It Matters |
|---|---|---|
| Jan 31 | W-2 / 1099-NEC | Give these to employees & contractors |
| Mar 1 | Delaware Franchise Tax | $200 late fee if missed |
| Apr 15 | Form 1120 + Q1 Estimated Tax | Corporate tax return & first payment |
| Jun 15, Sept 15, Jan 15 | Estimated Tax Payments | Avoid underpayment penalties |
💡 Pro tip: Use TaxHero AI’s Startup Tax Calendar to get all these dates auto-loaded and get reminders before they sneak up on you.
Simply answer a few questions and get the calendar in seconds, plus automated reminders to your email.
Click here - Tax Calendar
Yes, even that $12 Figma subscription and the $6 coffee you bought before your investor meeting.
Why? Because deductions add up, and the IRS is picky about documentation.
Categories to watch:
Software & tools
Marketing spend
Travel & lodging (yes, that founder retreat counts)
Contractor payments
Office expenses
👉 See our guide: 7 Tax Deductions You Shouldn’t Miss in 2025
If you paid a freelancer or contractor $600+ this year, you owe them a 1099-NEC.
Mess this up and you risk:
IRS penalties
Disgruntled contractors
A mess during due diligence if you raise funding
Full walkthrough here: 1099s for Startups: The Complete Guide for Founders
Even if you’re pre-revenue, you might qualify for thousands back via the R&D Tax Credit.
If you’re building something new — code, prototypes, designs — you could reduce your payroll taxes by up to $250K over five years.
See: R&D Tax Credit for Startups: How to Save Big Before You Even Launch
Stop juggling spreadsheets and sticky notes.
Tools like TaxHero AI:
Generate your personalized tax calendar
Send deadline reminders
Help you file on time
Flag missing forms before it’s too late
Because you don’t need to be a tax expert, you just need to avoid expensive mistakes.
Taxes don’t have to be chaos. A little structure + the right tools = more money in your pocket and less stress in your head.
Bookmark this guide, send it to your co-founder, and if you’re ready to take the mental load off, get your TaxHero AI.
Start by finding out what your company needs to do.
Start now See your deadlines for free.