Why a separate account works
Money in your main account feels available. Money in a different account with a clear name feels reserved. That small psychological barrier is the whole trick. Name the account something blunt, such as Taxes Do Not Touch, and avoid linking it to a debit card.
Keep it at the same bank if possible so transfers are instant, but do not set up overdraft protection from it into your spending account.
Choosing a percentage
There is no universal percentage. The right number depends on your profit, your filing status, your state, other income and whether you have employees. Ask your preparer for a starting figure based on last year's return and adjust it after your first quarter.
A percentage of every deposit is simple but can over-save when expenses are high. A percentage of profit is more accurate but needs current books. Many owners start with a percentage of deposits and refine it quarterly using the profit and loss report.
Make the transfer automatic and recorded
Transfer on a schedule, such as every time a client pays or on the first of the month. In the books, record the transfer as a transfer between accounts, not as an expense. Add the savings account to your accounting software so its balance appears on the balance sheet.
When you pay estimated tax, move the money out of savings into the payment. The balance in savings then shows what you still owe or have in reserve.
Separate sales tax and payroll tax money
Sales tax collected from customers and payroll withholding taken from employees are not your money. They belong to the government. If you handle these, consider a third sub-account or at least a tracked liability so those funds are not mixed with income tax savings.
A simple table works: one row each for income tax reserve, sales tax collected, and payroll taxes owed, with the current balance and next due date.
Review it every quarter
At each quarter close, compare the savings balance to the projected tax. If the account is ahead, you can lower the percentage. If behind, raise it or add a lump sum. A bookkeeper can build that quick comparison into the monthly report so you see it without asking.
If the balance ever runs far above what is needed, ask your preparer before spending it. A year with unusual deductions might lower tax, but a missed payment may carry a penalty.
A starting example without numbers
Suppose a consultant deposits client payments into the operating account. Each Friday the consultant moves a fixed share of that week's deposits into the tax account, notes the amount in the transfer memo, and logs it in the books as a transfer. At quarter end the consultant compares the savings balance to the amount the preparer projected.
That is the entire system. It works because it runs on a calendar, not on memory or on how the month felt.
Common questions
How much should I put in tax savings?
Ask your preparer for a figure based on your last return and expected profit, then review it every quarter. Avoid copying a percentage from a stranger online.
Should this account earn interest?
Interest is taxable income, so a savings account that earns interest is fine, and the interest should be reported.
What if I do not have the money to pay the tax?
Contact the tax agency early. Payment plans exist, and acting before the deadline usually costs less than ignoring the bill.
This guide is general information, not tax, legal or accounting advice. Rules, fees and due dates change; check with the IRS, the NJ Division of Taxation or a licensed professional for your situation.