How Much Should You Set Aside in a Tax Reserve?
Your tax reserve should cover the projected tax that withholding and estimated payments won't. Subtract what you've already saved, then divide the remaining gap by the customer payments you expect before year-end to get a transfer rate. Check that the money will be in the reserve before each tax payment is due, and update the rate when the numbers change.
Your tax bill has to compete with every other use for your cash. Payroll has a date. Software charges the card. Taxes get whatever you remember to move into savings.
Maybe you’ve fixed that by transferring 30% of every client payment. But 30% of what comes in isn’t necessarily what you still owe. Too little leaves you pulling cash back from plans you’ve already made. Too much leaves money sitting in tax savings while the business needs it elsewhere.
The goal isn’t a savings account that looks healthy. It’s knowing what belongs there, what each incoming payment needs to contribute, and whether the cash will be ready before the bill is due.
How Much Tax Do You Still Need to Fund?
You need a current tax projection, a record of what you've paid, and the amount already reserved. If you don't know what remains to be funded, that is the first number to establish.
Input | What it includes | Where it comes from |
Projected tax | Full-year tax after applicable credits, including self-employment tax where it applies, before subtracting withholding or estimated payments | A current tax projection |
Income tax withholding | Income tax withheld so far plus what's expected for the rest of the year, from wages, pensions, or other sources. Social Security and Medicare withholding don't count. | Payroll records and withholding statements |
Estimated payments | Payments already made for the same tax year | Payment confirmations |
Reserve cash | Money set aside now and available for these taxes | The reserve account balance |
Keep the taxpayer, the tax year, and the federal and state scope the same on every line. A federal projection matched against a record that includes state payments produces a gap that isn't real.
The projection is the one input this method doesn't produce. A reliable projection sets the tax target, and everything that follows is about funding it. Without one, there's no way to validate a transfer rate, and establishing it comes first. If you don't have a current projection, that's work we do with owners.
The target is your full projected liability. Safe harbor payments serve a different purpose, avoiding an underpayment penalty, and they can sit below what you'll owe. IRS Publication 505 treats the estimated-tax payment requirements and the tax itself as two different figures, which is why meeting one doesn't mean you've funded the other.
How Do You Turn That Gap into a Transfer Rate?
Divide the amount still to set aside by the customer payments you expect before year-end.
Transfer rate = amount still to set aside ÷ customer payments expected before year-end
Calculation | Illustrative amount |
Projected tax remaining after full-year income tax withholding and estimated payments already made | $50,000 |
Cash already reserved | −$20,000 |
Amount still to set aside | $30,000 |
Customer payments expected before year-end | $300,000 |
Starting transfer rate | 10% |
In this example, a $10,000 customer payment calls for a $1,000 reserve transfer. That 10% is a funding rate for the remaining gap, not the business's tax rate or a recommendation for every owner.
Customer payments means the cash you expect from customers, not every bank deposit. Loans and money you put into the business stay out of the funding base. Leaving them out keeps the transfer tied to customer cash and has no effect on how the business's income is taxed.
Two edge cases change the answer. If the amount still to set aside is zero or negative, the current projection calls for no additional funding, but confirm upcoming payments before releasing any cash. If no more customer payments are expected, or the transfer would take cash the business needs to operate, a percentage can't solve the funding problem.
Will the Money Be There by the Next Tax Deadline?
A rate that funds the full year can still leave the next payment short, so check each deadline on its own.
Will your current reserve plus the transfers arriving before the deadline cover the next payment?
Answering it takes the next payment's amount and due date, today's reserve balance, and the transfers you expect before that date. A customer payment expected the week after the deadline doesn't count toward it.
If the answer is no, change the funding plan now rather than relying on receipts that arrive afterward. Work out whether available cash or larger transfers from receipts arriving before the deadline can close the gap without putting operating payments at risk. If neither can, you need a different funding plan before the tax payment is due.
The annual rate isn't proof that every interim payment is funded. Federal estimated tax runs on specific payment periods, each with its own due date, as the IRS guidance on estimated taxes lays out.
Where Should You Keep the Reserve?
Keep it in a separate savings account you can reach before each due date. Keeping tax money in operating checking makes it easy to mistake it for cash available to spend. A separate account makes the reserve easier to protect and check.
Match the account to the taxpayer. Personal income tax, including the tax on an S-Corp owner's share of profit, is the owner's to pay, so the reserve for it sits with the owner. The business's payroll obligations, including tax withheld from wages, come out of business cash and stay out of the reserve. This is a recommended setup, not a legal requirement.
For an S-Corp owner, cash reaches a personal reserve through salary or distributions, and each carries its own treatment. The cash available before an owner withdrawal depends on what the business needs first, so the reserve transfer follows that decision rather than replacing it.
When Should You Recalculate the Rate?
Recalculate every quarter, and sooner after a material change. A monthly check sits between recalculations.
Check | Schedule | What it confirms |
Funding check | Once a month | Scheduled transfers happened, and the next payment remains funded |
Rate recalculation | Once a quarter, or after a material change | The projection and expected customer payments are current, and the rate matches the remaining gap |
A material change includes a shift in profit, a change in when customers pay, or a change in expected withholding. A delayed client payment matters with no change to the tax projection, because it can move cash past a deadline.
Quarterly tax planning is where the projection gets refreshed, so the rate recalculation belongs on the same schedule.
When a payment goes out, it lowers both the reserve balance and the tax still unpaid. Record both sides, and don't subtract the same payment twice when you recalculate, since it now sits in the estimated payments line. A scheduled payment isn't a completed one, and IRS Direct Pay lets you confirm a federal payment's status.
Put the Next Transfer on the Calendar
Five steps turn the method into a date on your calendar.
- Establish the remaining tax target from a current projection.
- Confirm the reserve cash available for those taxes.
- Calculate the transfer rate against expected customer payments.
- Check that the next payment is funded by its due date.
- Schedule the next transfer and the next review.
You're finished when you know the amount and date of your next transfer.
The method holds as long as the books and the projection stay current together. At Visor, current books and quarterly tax planning work together inside one accounting operating system. That connects the tax target to the business numbers behind it. A free Visor account shows how those pieces fit together, using sample data, before you connect anything.
Not sure whether your reserve will cover the next payment? We can help you work through the numbers. Talk to our team — Free
Frequently Asked Questions
How much should a small business set aside for taxes?
Your reserve should cover the projected tax that withholding and estimated payments won't. Subtract what's already in the reserve to find how much more you need to save. Divide that gap by expected remaining customer payments to calculate your transfer rate, then check whether those transfers will arrive before each tax deadline.
Where should I keep my business tax reserve?
In a separate savings account you can draw on before each due date, held by the taxpayer who owes the tax. For income tax on an S-Corp owner's share of profit, that's the owner. Keeping it apart from operating cash makes the balance easy to check and harder to spend by accident.
How often should I true up my tax reserve?
Check funding once a month and recalculate the rate once a quarter, or sooner after a change in profit, customer payment timing, or withholding. Between recalculations, judge the reserve against the next payment rather than the full year. A balance below the year's remaining tax can still be on schedule when planned transfers cover each deadline. Neither schedule is an IRS rule.
Unable to reconcile the projection with your reserve? Talk to our team — Free
