Tara installed three full HVAC systems for a homebuilder in Phoenix during the last week of December. The invoices went out the same day, total $48,000, net-30. She also took delivery of $9,000 in equipment that month and put it on the supplier's account.
Then she pulled her December numbers and nearly called her bookkeeper to report an error. Revenue for the month came in close to zero. The month she worked hardest looked like the slowest month of the year.
Nothing was broken. Tara keeps her books on the cash basis, so December showed only what hit her bank account. The $48,000 landed in mid-January. The equipment bill cleared in January too. Her busiest December in years recorded almost no activity, and a quiet January suddenly looked like a blowout.
Same business, same work, two completely different stories. The difference comes down to one decision every business makes, often without realizing it: cash basis or accrual basis.
What an accounting method actually is
An accounting method is the set of rules that decides when a dollar shows up on the books. Before you can report income, you have to define what income means.
- Does it mean you made the sale?...
- Delivered the service?...
- Collected the payment?...
The IRS recognizes two answers, and the gap between them is the timing of recognition.
Cash basis: follow the money
On the cash basis, revenue is recognized when the money is received and an expense is recognized when the bill is paid. Do the work in November, get paid in January, and the income belongs to January. Receive a utility bill in March, pay it in April, and the expense belongs to April.
This method is simple. The books roughly match the bank statement; there are no accounts receivable or accounts payable to track, and tax is owed only on cash actually collected. Freelancers, sole proprietors, and small service businesses lean on it because it mirrors how money really moves through the account.
The weakness shows up in months like Tara's. Cash-basis numbers can make a strong month look dead and a slow month look spectacular, purely because of when checks clear.
Accrual basis: follow the work
On the accrual basis, revenue is recognized when it is earned and an expense is recognized when it is incurred, no matter when cash changes hands. Finish a project in December, and the income counts in December, even if the client pays in February. Receive that equipment in December, and the expense counts in December, even if the bill is paid later.
This is the matching principle at work, the core of GAAP (Generally Accepted Accounting Principles). Revenue gets paired with the expenses that produced it inside the same period:
Accrual profit = revenue earned in the period − expenses incurred to earn it
That pairing is why accrual gives a truer read on profitability. It also adds work. Accrual books require tracking accounts receivable, accounts payable, prepaid expenses, and unearned revenue, which usually means accounting software or a bookkeeper.
The same transaction, both ways
Take Tara's December and lay it side by side. Two events: the $48,000 in installs (earned in December, paid in January) and the $9,000 equipment bill (incurred in December, paid in January).
| Line |
Cash basis |
Accrual basis |
| December revenue |
$0 |
$48,000 |
| December expense |
$0 |
$9,000 |
| December profit |
$0 |
$39,000 |
| January revenue |
$48,000 |
$0 |
| January expense |
$9,000 |
$0 |
| January profit |
$39,000 |
$0 |
Same $39,000 of real profit. Cash basis parks it all in January. Accrual basis records it in December, the month the work was done. Neither number is wrong. They answer different questions. Cash basis answers what landed in the account. Accrual basis answers what the business has actually earned.
Which method the IRS lets you use
Both methods are legal under Internal Revenue Code Section 446, which requires only that the method clearly reflect income and remain consistent from year to year. Size decides how much freedom you get.
The deciding number is the small business taxpayer threshold under Section 448(c). For 2026 it sits at $32 million in average annual gross receipts over the prior three years, up from $31 million in 2025. Stay at or below it, and you can choose cash, accrual, or a hybrid, even if you carry inventory. Clear it and accrual becomes mandatory.
One rule keeps cash-basis filers honest: constructive receipt. Income counts the moment it is available to you, not the day you deposit it. A client's check sitting unopened in your mailbox on December 31 is still December income. Leaving it there does not push the tax into the next year.
Choosing the one that fits
A freelancer or service business with no inventory and simple money-in, money-out activity is usually well served by the cash basis. It is easier to run, and it matches the bank balance.
A business that carries inventory, bills clients on terms, runs projects across month or year boundaries, or plans to raise money tends to need accrual. Lenders, investors, and buyers expect accrual statements because they show receivables and payables, not just cash on hand.
A common middle path keeps the tax books on cash for simplicity and runs management reports on accrual to see real performance. Good software produces both views from the same data set.
Back to Tara. For taxes, cash basis keeps filing simple and ties the bill to money she has actually collected. For running the company, accrual shows that December was her strongest month of the year, revealing the truth that her bank balance had hidden for six weeks. She does not have to pick one and lose the other. She just has to know which question each set of numbers is answering.
