How much cash should a landlord keep in reserve for rental properties?

Operating reserve versus capital reserve

A capital reserve is set aside each month for big replacements, such as a roof, a boiler or flooring. The capital reserves guide covers that. An operating reserve is different: cash that keeps the property paying its bills when income dips, such as a vacancy, a late-paying tenant or a surprise repair.

Keeping them separate stops one from quietly spending the other. Treat them as two lines on the balance sheet, even if they sit in one bank account.

How to size it

1. Add up the monthly costs that continue with zero rent: mortgage payment, property tax, insurance, utilities you pay, and a basic amount for upkeep.
2. Decide how many months you want to cover. Three is a common starting point, six is more cautious, and a single vacant unit in a 2-unit building is a bigger risk than one unit in 40.
3. Add your highest insurance deductible, since it is cash you pay before a claim starts.
4. Subtract nothing for security deposits. They are held for tenants, not for you to use (see below).

Example a made-up 4-unit building costs $2,900 a month in mortgage, $650 in property tax, $320 in insurance and $330 in utilities and upkeep, which adds to $4,200 a month. Six months is $25,200. The insurance deductible is $2,500, so the target is $27,700.

Smaller buildings need a larger cushion per unit because one vacancy is a bigger share of income. A larger portfolio spreads the risk, so the months you hold can be fewer.

Security deposits are not part of your reserve

Tenant deposits belong to the tenant until you have a lawful reason to deduct from them. Many states require them to be held in a separate account, and mixing them with your own cash can cause legal and tax problems. See security deposits as a liability. If your operating account shows $30,000 and $12,000 of it is deposits, you have $18,000 of reserve.

Where to keep it

• In the bank account of the property's LLC, if you use one LLC per property, so each property carries its own cushion.
• In an account you can reach in a day, such as a savings account, not in an investment that can drop in value when you need it.
• Not mixed with your personal funds. Mixing weakens the separation an LLC is meant to give. See commingling.

Refill it first when you spend it. A reserve that is used and not rebuilt is not a reserve. After a draw, pause owner distributions and extra projects until the balance is back at your target, and write down the date it was spent and the date it was restored, so the next time you have a number to plan with.

How DoorKeeping handles it

DoorKeeping keeps one set of books per property and shows each property's income, expenses and deposits held, so you can ask Claude or ChatGPT "how many months of expenses does each property's bank balance cover, after deposits?" and see where a cushion is thin. Rent stays in your own bank account, and anything involving money waits for your approval.

Sources

1. DoorKeeping: Connect Claude or ChatGPT (steps and tools list), read Oct 30, 2026

Questions

How many months of expenses should a landlord keep in reserve?

Three to six months is a common rule of thumb. Your number should reflect your property's costs, its size, and how fast you can re-rent.

Are security deposits part of my reserve?

No. Deposits belong to your tenants until you have a lawful reason to deduct, and many states have rules for holding them.

What is the difference between an operating and a capital reserve?

An operating reserve covers bills when income dips. A capital reserve is set aside for big replacements such as roofs or boilers.

Where should I keep a reserve?

In an account you can reach quickly, separate from personal money, and ideally in the property's own LLC account.