For corporations, estimated taxes can be calculated using the Worksheet: Form 1120-W. For sole proprietors and individuals, the estimated taxes can be calculated using the Worksheet: Form 1040-ES
Typically, you can also calculate the estimated taxes based on the following aspects.

• Previous Year's Tax Liability: If the income and expenses of you or your business remain the same all the years, use the previous year's tax liability as a basis for estimating the current year's tax liability.
• Current Year's Income and Expenses: You can use the current year's income and expenses to determine your expected taxable income.
• Tax Law Changes: While calculating estimated taxes, it's important to consider any recent changes in tax laws that might affect the tax liability. This includes changes in tax rates, deductions, credits, and more.
• Tax Credits and Deductions: Make sure to include any tax credits and deductions that you are eligible for when estimating your business/personal tax liability. For example: Depreciation, and credits for research and development, renewable energy, etc.