# Discover premium tax resources for startups and small businesses

Our custom calculators, expert-written articles, and webinars will help prepare your company for tax season—or any season.

## Popular articles

**Author:** The Carta Policy Team  
**Date:** October 2023  
**featured article**  
**Title:** Tax planning for small businesses  
**Description:** Small businesses owners and entrepreneurs can use these tax planning strategies to save on taxes and maximize business growth.

**Author:** Founder Education  
**Date:** March 2026  
**Title:** Business tax deadlines 2026: Corporations and LLCs  
**Description:** Key tax deadlines are coming up in 2026 for LLC and corporation businesses. Here are the dates and IRS forms you need to know.

**Author:** Founder Education  
**Date:** April 2025  
**Title:** How taxes work for LLCs  
**Description:** Learn how LLC taxation works, what makes LLCs “pass-through” entities, how different types of equity are taxed, and why LLCs avoid double taxation.

**Author:** Equity Education  
**Date:** November 2022  
**Title:** Tax advisors  
**Description:** A tax advisor works with you to model different scenarios that can help minimize your tax liability while staying compliant with the U.S. tax code.

## Documents and forms

[**What is a Schedule K-1 tax form?**](https://fund-forecasting@carta.com/sg/en/learn/startups/tax-planning/schedule-k-1-tax-form/)

[**Understanding Form 1120-S: Tax return for an S-Corporation**](https://fund-forecasting@carta.com/sg/en/learn/startups/tax-planning/form-1120s/)

[**What is Form 3921?**](https://fund-forecasting@carta.com/sg/en/learn/startups/equity-management/form-3921/)

## Understanding QSBS

[**The qualified small business stock (QSBS) tax benefit**](https://fund-forecasting@carta.com/sg/en/learn/startups/tax-planning/qsbs/)

[**Introducing QSBS Attestation**](https://fund-forecasting@carta.com/sg/en/product-updates/introducing-qsbs-attestation/)

[**QSBS stacking and packing**](https://fund-forecasting@carta.com/sg/en/learn/startups/tax-planning/qsbs/stacking-packing/)

**How to pay less taxes on your startup shares**  
In this episode of Startup Essentials, we break down all the basics that founders, employees, and investors need to know about QSBS — a federal tax exclusion that could provide an enormous tax break when selling shares of a company.  
**[Watch now](https://www.youtube.com/watch?v=X2uXqDYq02g)**

## Popular tools

[**QSBS calculator** 
View tool](https://fund-forecasting@carta.com/sg/en/learn/resources/qsbs-calculator/)

[**2025 AMT calculator** 
View tool](https://fund-forecasting@carta.com/sg/en/amt-calculator/)

[**Tax season resources** 
Learn more](https://fund-forecasting@carta.com/sg/en/resources/tax-filing-season/)

## Taxes and employee equity

**Author:** The Carta Team  
**Date:** March 2024  
**Title:** Form 6251 and AMT  
**Description:** IRS Form 6251 is a worksheet that helps you determine if you owe AMT and how much. You can also calculate your estimated AMT using our AMT calculator.

**Author:** Equity  
**Date:** January 2026  
**Title:** Filing an 83(b) election: What every founder needs to know  
**Description:** Learn what a Section 83(b) election is and how it can lower your future tax bill. Get clarity on important due dates, filing information, and what to include in form 83(b).

**Author:** Equity  
**Date:** January 2026  
**Title:** How stock options are taxed: A complete guide  
**Description:** Learn about stock options taxes, including the tax treatment differences between ISOs and NSOs, holding periods, exercising, and the alternative minimum tax.

**Author:** Founder Education  
**Date:** October 2022  
**Title:** How to answer three common employee stock option tax questions  
**Description:** Learn how to think about answering questions about stock options and taxes—and when you should direct employees to a third-party Equity Tax Advisor.

**Author:** Taxes  
**Date:** April 2026  
**Title:** The alternative minimum tax (AMT), explained  
**Description:** Learn about the alternative minimum tax (AMT), how it can create a tax liability when you exercise incentive stock options, and how to calculate AMT for your tax return.

**Author:** Employee Resource Center  
**Date:** June 2024  
**Title:** Cashless exercise  
**Description:** Learn how a cashless exercise of stock options works, including tax implications to consider when exercising ISOs or NSOs.

**Author:** Equity Education  
**Date:** July 2022  
**Title:** The $100K ISO limit  
**Description:** The ISO $100K limit prevents employees from treating more than $100,000 worth of exercisable options as incentive stock options in a single year. Learn more.