How Much Emergency Cash Should My Small Business Keep?

By Bill Stilwell · Last reviewed October 16, 2026

The short answer

A cash reserve is money you keep set aside for slow periods, repairs, taxes, emergencies, and surprises. Set a target based on your monthly fixed costs and your slowest stretch of the year, keep it in a separate account, and build it a little from every payment. Set aside tax money separately so the reserve isn’t spent on a tax bill you knew was coming.

What this means

The outline asks you to set a target reserve for slow periods, repairs, taxes, emergencies, and unexpected costs.

A reserve covers things like:

Slow periods: the months below break-even (see 7.4.3 Seasonality)
Repairs: a broken truck, mower, or computer
Taxes: estimated tax payments and year-end bills
Emergencies: an injury, a lost client, a storm
Surprises: a price jump, a big refund, a late-paying customer

Startup cash gets you to break-even (see 7.8.12 Cash Needed Before Customers Pay). The reserve is what you keep after that.

Example: a lawn care business has fixed costs of $4,000 a month and two slow winter months. The owner sets a reserve target of 3 months of fixed costs, plus enough to replace a commercial mower. The owner moves 10 percent of every payment into a separate savings account until the target is reached, and keeps tax money in a different account.

Why it matters

Slow months are certain. Their timing isn’t. Weather, the economy, or a lost customer can drop sales without warning.
Repairs don’t wait. If the truck breaks and you can’t fix it, you can’t work.
Tax bills can be large. The Internal Revenue Service (IRS) says individuals, including sole proprietors and partners, generally must pay estimated tax if they expect to owe $1,000 or more when they file. Payments are due in four periods during the year, and missing one can bring a penalty.
It keeps you from bad debt. Without a reserve, owners often turn to high-interest credit cards in a pinch.

Who this applies to

Every business. It matters most for seasonal businesses, businesses that depend on equipment or vehicles, and those with a few large customers.

How to do it

Start with your monthly fixed costs (see 7.8.10 Fixed Costs).
Look at your demand calendar. Count the slow months and how far below break-even they fall.
List the big repairs or replacements that could stop work, and their rough cost.
Set a target. A common starting point is a few months of fixed costs, adjusted up for seasonal or equipment-heavy businesses. Write your number and the reason.
Open a separate business savings account for the reserve (see 10.4.3 Payroll and Savings Accounts).
Set aside tax money in its own account, separate from the reserve (see 10.4.2 Tax Reserve Account). Ask your certified public accountant (CPA) what share of each payment to save for taxes.
Move a set share of every customer payment into the reserve until you hit the target.
Write down when it’s OK to use the reserve, such as a slow month below break-even or a repair that stops work. Write down when it’s not, such as new equipment you want but don’t need.
Refill it after you use it.
Review the target once a year or when fixed costs change.

What proof to keep

Your written reserve target and how you set it
Bank statements showing the separate reserve and tax accounts
A log of each time you used the reserve, why, and when you refilled it

Keep these with your bookkeeping records.

Common mistakes

Mixing the reserve with daily money. If it’s in the operating account, it gets spent. Keep it separate.
Using the reserve for taxes. Taxes are expected. Save for them in their own account.
Setting a target and never funding it. Automate a small transfer from every payment.
Raiding it for wants. Write your use rules down before you need them.
Never refilling it. A reserve that’s half empty is only half a reserve.

When to get help from a pro

Talk to a CPA about how much to set aside for taxes and how estimated payments work for your business type. Rules differ for corporations and by state. Ask:

What share of each payment should I save for federal and state taxes?
When are my estimated tax payments due, and how should I figure them?

Bill’s note

[Bill: add a short story or opinion here. For example, how you set SiteSmarty’s reserve target, or a client whose reserve kept them going through a slow stretch.]

How I did this for SiteSmarty

[Date I did this:]
[What I actually did, step by step: my reserve target, how I set it, and how I’m building it]
[What it cost and how long it took:]
[What surprised me or what I’d do differently:]
[Screenshot or photo to add, with private info blurred: my reserve target and the separate savings account with the balance blurred]
[Result so far:]

Questions people ask

How much cash reserve should a small business have? It depends on your fixed costs, how seasonal you are, and what could stop your work. Many owners start with a few months of fixed costs and adjust from there. Talk to a CPA about your case.

Where should I keep my reserve? In a separate business savings account, not your operating account, so it isn’t spent by accident.

How do I save for taxes? Keep a separate tax account and move a set share of each payment into it. The IRS generally expects estimated payments during the year if you’ll owe $1,000 or more. Ask a CPA what share to save.

When is it OK to use the reserve? For the things you wrote down in advance, like a slow month below break-even or a repair that stops work. Refill it afterward.

Audit check

Question: Does the business have a written cash reserve target, a separate reserve account, and a separate tax account?
Pass looks like: A written target with the reasoning, a separate savings account being funded from each payment, a separate tax account, written use rules, and a use log.
Fail looks like: No target. Reserve kept in the operating account. Tax money mixed with the reserve. No use rules.
Evidence to collect: The written target, bank statements for both accounts, the use rules, and the use log.

Where this fits

Do this first: 7.8.13 Maximum Customer Acquisition Cost, 7.8.10 Fixed Costs

Do this next: 7.9 Proceed, Revise, or Stop Decision

Sources

Internal Revenue Service, "Estimated taxes" (checked October 16, 2026)
U.S. Small Business Administration, "Calculate your startup costs" (checked October 16, 2026)

This page explains general rules and Bill's own experience. It is not legal, tax, or insurance advice. Talk to a qualified professional about your situation.