Chapter 2: Tax Accounting Methods and Periods#

When you earn money or spend it, the tax code doesn’t just ask whether something is taxable or deductible — it also asks when. This chapter is your guide to that timing puzzle. We’ll look at the two main ways taxpayers count income and expenses, and then walk through a set of special rules that tell you exactly when a dollar hits your tax return.

The Big Picture#

Every tax calculation starts with a simple question: which year does this item belong to? A business might get cash in December but not finish the work until January. A homeowner might pay points to get a mortgage and wonder if that’s an instant deduction. Tax law uses accounting methods and timing rules to answer these questions. The goal is to match income and expenses to the right tax year in a way that clearly shows economic reality — and, just as importantly, to stop people from playing with timing to dodge taxes. By the end of this chapter, you’ll understand the cash and accrual methods, how prepaid expenses and interest are handled, and why some costs must be spread over many years.

Cash Receipts and Disbursements Method#

Most individuals and many small businesses use the cash method of accounting. Under this method, you report income in the year you actually or constructively receive it, and you deduct expenses in the year you actually pay them.

Cash method: A tax accounting method where income is counted when cash, property, or services are received, and deductions are taken when payment is made.

Constructive receipt means income is yours to use even if you haven’t physically pocketed the cash. If a client’s check arrives on December 30 and you just choose not to deposit it until January 2, the IRS still treats that income as received in the earlier year because you had free access to it. The same idea applies to interest credited to your bank account — it’s income the moment it’s posted, whether you withdraw it or not.

On the deduction side, the rule is straightforward: you deduct an expense in the year you pay it. Write a check for office supplies on December 28 and mail it that day — that’s a current-year deduction, even if the check clears in January. But if you merely promise to pay or get a bill, that doesn’t count; the cash must actually leave your hands. Credit card charges are a notable exception we’ll cover later.

The cash method is simple and easy to follow, but it has limits. Businesses with inventory generally cannot use it, and larger corporations often must switch to accrual. Still, for many taxpayers, it’s the default and most practical approach.

📝 Section Recap: The cash method ties income to the moment you get money (or could have gotten it) and deductions to the moment you pay. It’s simple but not always allowed.

Accrual Method: The All-Events Test and Economic Performance#

Larger businesses and those with inventory usually use the accrual method. Instead of waiting for cash to change hands, the accrual method counts income when it is earned and deductions when a liability becomes fixed and the amount can be figured out — even if payment hasn’t happened yet.

Accrual method: A tax accounting method that reports income when the right to receive it is set and deductions when all events have happened that fix the liability and the amount can be worked out with reasonable accuracy.

The rule for income is fairly direct: if you’ve done the work or delivered the goods and the customer must pay, you book the income now, no matter when the check arrives.

Deductions are trickier. The tax code imposes a two-part test known as the all-events test. First, all the events that set up your liability must have happened. Second, the amount must be possible to work out with reasonable accuracy. But even if both parts are met, you still cannot deduct the expense until economic performance has occurred.

Economic performance: The actual delivery of goods or services, or the actual use of property, that triggers the right to deduct an accrued liability. For services, it happens when the services are done; for property, when the property is used or provided.

Think of a company that hires a consultant in November. The consultant finishes the work in December and sends a bill for 10,000 in December, even if it pays the invoice in January. If the consultant hadn’t started the work until January, no deduction would be allowed in December, because economic performance hasn’t happened yet.

A few narrow exceptions let you deduct certain recurring items before economic performance, but the general rule is that you must wait until the other party actually delivers what they promised. This stops businesses from speeding up deductions just by signing a contract.

📝 Section Recap: The accrual method ties income to the right to receive it and deductions to a fixed, workable liability for which economic performance has occurred — not just a promise to pay.

Prepaid Expenses and the 12-Month Rule#

What happens when you pay for something that will help you well beyond the current year? Say you pay 36,000 right away. But tax law says no — that payment creates a future benefit, so it must be capitalized and deducted over the period it covers.

Capitalize: To treat an expense as an asset and recover its cost over time through depreciation, amortization, or spreading it out, rather than deducting it immediately.

The general idea is that prepaid expenses that create benefits stretching far beyond the end of the tax year must be spread out. However, there’s a helpful safe harbor called the 12-month rule. If you pay for a benefit that will be used up within 12 months after you first start getting the benefit — and the contract period does not go beyond the end of the tax year after the year of payment — you can deduct the whole amount in the year you pay.

12-month rule: A rule that lets you deduct a prepaid expense right away if the benefit period is 12 months or less and does not go beyond the end of the tax year after the year of payment.

For example, you pay 12,000 in 2025. But if the policy were for 13 months, or if it ran from July 1, 2025, to December 31, 2026 (stretching beyond the next tax year), the rule would not apply — you’d have to capitalize and spread out the cost.

This rule avoids the hassle of precise day-by-day math for short prepayments, while still stopping large, multi-year prepayments from being deducted all at once.

📝 Section Recap: Prepayments for future benefits generally must be capitalized and deducted over time, but the 12-month rule lets you deduct right away if the benefit is used up within 12 months and doesn’t stretch beyond the following tax year.

Prepaid Interest and Original Issue Discount#

Interest payments get special timing treatment because they stand for the cost of using money over time. If you pay interest in advance — or if a loan is set up so that interest is built into the repayment price — the tax code makes you spread that cost over the life of the loan.

Prepaid Interest and Points#

When you take out a mortgage, you may pay points (also called loan origination fees or discount points) to reduce your interest rate. Each point equals 1% of the loan amount. In real terms, points are prepaid interest. The general rule is that points are not fully deductible in the year you pay them; instead, you must spread the deduction over the term of the loan.

Points: Upfront fees paid to a lender at closing, treated as prepaid interest, generally deductible over the life of the loan rather than right away.

For a 30-year mortgage, that means deducting a small piece each year. However, if you use the loan to buy or improve your main home and certain other conditions are met, you may deduct the points in the year paid. But for business loans, rental property loans, or refinancing, the default is to spread points over the loan’s length.

The same idea applies to any prepaid interest: if you pay interest in advance for a period that goes beyond the current year, you must spread the deduction across the years the interest belongs to.

Original Issue Discount (OID)#

Some loans are issued at a discount — you borrow 1,000 in five years, with no stated interest. The $100 difference is original issue discount (OID) , which is really interest that builds up over the life of the loan. Even though no cash interest payments are made, the tax law treats OID as interest that both the borrower and lender must account for each year.

Original issue discount (OID): The difference between a debt instrument’s stated payoff price at maturity and its issue price, treated as interest that builds up over the life of the loan.

The borrower deducts, and the lender reports as income, a piece of the OID each year according to a constant-yield method. This stops borrowers from pushing interest deductions to the end and lenders from putting off interest income. The math uses the original yield to maturity to spread the discount evenly in economic terms, though the actual dollar amounts grow slightly each year.

For example, if a company issues a five-year zero-coupon bond with a 783.53, the OID is $216.47. Over five years, the borrower deducts and the bondholder reports that OID as it builds up, even though no cash changes hands until the end.

📝 Section Recap: Prepaid interest, including points and OID, must be spread over the loan’s life to match the cost of borrowing with the periods that benefit. Immediate deduction is the exception, not the rule.

Disputed Liabilities and Escrow Payments#

Sometimes you owe money but disagree about the amount or whether you owe it at all. The tax code has a specific rule for disputed liabilities to stop you from deducting an amount you’re still arguing about.

If you contest a liability but hand over money to satisfy it — for example, by paying the disputed amount into an escrow account or to a court — you may deduct it in the year of the transfer, as long as certain conditions are met. The key requirement is that the payment must actually be made; just setting aside funds in your own account won’t work. The transfer must be to a third party outside your control, and the liability must be one that would have been deductible except for the dispute.

Disputed liability: An obligation whose existence or amount is being contested. A deduction is allowed in the year the taxpayer transfers money or property to satisfy the liability, even if the dispute continues.

Imagine a business gets a bill for 50,000 into an escrow account managed by the court while the lawsuit goes on. Under the disputed liability rule, the business can deduct the $50,000 in the year the escrow payment is made, even though the legal fight isn’t settled. If the business later wins and gets the money back, that recovery becomes income in the year it’s returned.

This rule makes sure taxpayers aren’t forced to wait years for a deduction just because they’re defending themselves in good faith.

📝 Section Recap: A taxpayer who pays a disputed amount into escrow or to a third party may deduct it right away, as long as the payment would otherwise be deductible, with any later recovery taxed as income.

Business Investigation and Start-Up Costs#

Launching a new business or looking into expansion means spending money before any revenue shows up. Tax law sets apart costs to check out a new business, costs to actually start one, and costs to expand an existing business. The treatment can be surprisingly different.

Investigating an Existing Business Expansion#

If you already run a business and you spend money checking out an expansion within the same line of business, those investigation costs are generally currently deductible as ordinary and necessary business expenses. There’s no requirement to capitalize them. For example, a restaurant owner who pays a consultant to study a possible second location in the same city can deduct that fee right away.

But if you’re checking out a fully new trade or business — one you aren’t already in — the costs are treated as start-up costs, subject to the rules below.

Start-Up Costs and Organizational Costs#

Start-up costs are amounts paid to look into creating or buying an active trade or business, or to actually create the business, that would be deductible if the business were already running. They include market surveys, ads before opening, employee training, and professional fees for setting up the business. However, once you’ve decided to start the business, costs incurred to buy specific assets (like equipment or a building) are capitalized as part of the asset’s basis, not treated as start-up costs.

Start-up costs: Expenses to look into or create a new trade or business, which must be capitalized but can be partly expensed and spread out under special rules.

The tax code gives a limited immediate deduction for start-up costs. You can deduct up to 5,000 is reduced dollar-for-dollar (phased out) when total start-up costs go above 55,000 or more, the immediate deduction is fully phased out. Any remaining start-up costs after the immediate deduction must be amortized (deducted evenly) over 180 months, starting with the month the business begins.

For example, say you have 5,000 immediate deduction is reduced by 50,000), so you can deduct 49,000 is amortized over 180 months. If you had 5,000 is wiped out entirely, and you amortize the full $60,000 over 180 months.

Organizational costs follow an identical rule. These are expenses to form a corporation or partnership — legal fees for drafting the charter, filing fees, and temporary director meetings. The same 50,000) applies, with the rest amortized over 180 months.

Organizational costs: Expenses directly tied to creating a legal business entity, eligible for the same $5,000 immediate deduction and 180-month amortization as start-up costs.

This two-part system — a small immediate write-off plus long amortization — balances the wish to help new businesses with the tax policy of matching costs to the income they eventually bring in.

📝 Section Recap: Costs to look into expanding the same business are currently deductible. But start-up and organizational costs for a new business get a limited immediate deduction (up to 50,000) with the rest amortized over 180 months.

Credit Card Charges and Timing#

One of the most taxpayer-friendly timing rules involves credit cards. When you charge a deductible expense to a credit card, the tax law treats it as paid on the date of the charge — not when you later pay the credit card bill. This applies to both cash-method and accrual-method taxpayers.

Credit card charge rule: A deductible expense paid by credit card is treated as paid on the date the charge is made, letting you take a deduction in that year even if the card balance is paid later.

This rule can be a helpful planning tool. Say you need new computers for your business and you charge 8,000 on your 2025 tax return. The IRS sees the credit card transaction as equal to borrowing money from the card issuer and then using that money to pay the vendor — so the payment to the vendor is viewed as complete at the point of sale.

The same idea applies to debit cards and electronic payments: the deduction is allowed in the year the funds move, not when the bank statement arrives. But be careful — if you merely get a bill and haven’t paid it, a cash-method taxpayer cannot deduct it until payment is made. The credit card rule is a specific exception that speeds up the deduction to the date of the charge.

📝 Section Recap: Charging an expense to a credit card gives you a deduction in the year of the charge, no matter when you repay the card issuer — a handy timing advantage for year-end purchases.

Summary#

You’ve just walked through the landscape of tax timing — from the plain cash method to the detailed rules for prepaid interest and start-up costs. The common thread is that the tax system cares deeply about when income and expenses land, not just what they are. By understanding cash versus accrual, the 12-month rule, OID amortization, and the special treatment of credit card charges, you can plan transactions with confidence and avoid nasty surprises. Remember, the law often makes you spread deductions over time, but it also gives you a few helpful shortcuts.