Seasonal Cash Reserve: How Much to Set Aside

Why this matters

Most service trades are seasonal. Cooling work peaks in summer, heating in winter, lawn and exterior work swing hard with the weather, and almost everyone has a stretch where the phone goes quiet. Overhead does not take the season off - rent, payroll, insurance, and truck payments roll in every month regardless. A cash reserve is the bridge that carries fixed costs across the lean months on the profits earned in the fat ones. Get the size right and the slow season is a planned dip, not a panic.

What a reserve is for, exactly

A seasonal cash reserve is money deliberately set aside in the busy months to cover the gap when revenue falls below your fixed costs. It is not your profit, not your tax money, and not your equipment fund. It is one job: keep the doors open and the team paid through the trough. Mixing it with other cash is how it disappears right before you need it.

Step one: find your monthly burn

Your burn is what the business must spend each month no matter how slow it gets. Total your fixed costs - overhead plus the payroll you intend to keep through the slow season plus debt payments. Strip out the variable costs that fall when work falls (materials, sub costs, fuel scale down with the job). What is left is the floor you have to cover each lean month. That floor is the number the reserve has to feed.

Step two: size the trough

Two things set how big the reserve must be:

• How deep the slow season runs. Some trades drop to a fraction of peak revenue, others just soften. The deeper the drop below your burn, the bigger the monthly gap to cover.
• How long it lasts. A four to six week lull needs far less than a three to four month off-season.

Multiply the monthly gap (burn minus whatever revenue still comes in during the slow months) by the number of slow months. That product is your minimum seasonal reserve - the cash needed to bridge the trough as it actually is, not as you hope it will be.

Step three: add a safety layer

The trough math gives you the bare bridge. Real life is rougher than the average, so add a buffer:

• A general operating cushion on top of the seasonal bridge, sized to a few months of burn, so a surprise (a truck dies, a big customer pays late, the season runs long) does not break you.
• Trade-standard practice points most small service businesses toward holding several months of fixed operating expenses in reserve as a baseline, with seasonal businesses leaning to the higher end of that range because their swing is sharper.

So the target is the seasonal bridge or the general cushion, whichever is larger, not one instead of the other.

How to build it without feeling the squeeze

You cannot conjure a reserve in the slow month, that is the month it gets spent. It has to be skimmed during the peak:

• Set a percentage of every busy-season deposit aside automatically, into a separate account you do not touch for operations. Treat it like a bill the business pays itself.
• Size that percentage off the trough math. If the slow season needs a certain bridge and the busy season runs a certain number of months, the share of peak revenue you must save is just the bridge divided by peak income. Save that share off the top, every job, all season.
• Keep it separate and slightly inconvenient to reach. A reserve in the operating account is a reserve that gets spent on something that felt urgent in July.

Reading whether your reserve is healthy

A few signals tell you if you are on track:

• Reserve covers the full trough at current burn. If it does not, you are one slow season from borrowing expensively. Raise the save rate.
• You enter the slow season with the reserve full, not half-spent. If it is already drained going in, something else is eating it - usually under-pricing or owner draws.
• The reserve refills every peak. A reserve you raid and never rebuild is a one-time loan from yourself, not a system.

What this prevents

A funded reserve is what keeps you from laying off good techs you will need back in spring, from borrowing at bad rates to make payroll, and from taking unprofitable work just to generate cash in a dead month. The discipline is simple and the payoff is large: save aggressively when it rains, spend the reserve calmly when it does not.

References

• U.S. Small Business Administration: cash-flow planning and reserve guidance for seasonal businesses.
• Standard practice on operating reserves and months-of-expense coverage.
• See related: Reading an Aging Report, Who to Chase First.
• See related: Profit First vs Traditional Accounting.