Know your quarterly number before the IRS asks.

Three IRS methods, not one flat percentage

Most apps tell you to set aside 30% and hope. Neeuh uses the rules the IRS applies to estimated payments.

• Current-year method: 90% of this year's tax, less any withholding.
• Prior-year safe harbor: 100% of last year's tax, or 110% if your AGI was over $150,000. Enter last year's figure and Neeuh uses it.
• Annualized-income method (Form 2210, Schedule AI) for lumpy income, switched on in tax settings.

Self-employment tax included

Social Security and Medicare on your net earnings are part of the estimate, not a surprise at filing time. The tax calculator breaks them out line by line.

State income tax

Neeuh estimates state income tax alongside federal using each state's brackets for the year.

Deadlines you won't miss

Every quarterly due date is on your tax screen. Turn on email reminders and Neeuh writes 14, 7 and 1 day before each one. When it is time to pay, it links you straight to IRS.gov.

Updates as money moves

Each new transaction, split or mileage entry changes the estimate, so the number you see is today's, not last month's.

S corporation owners, too

Add your owner salary and distributions in the S-corp setup and the estimate accounts for them.