Publication 538 Summarized — Accounting Periods and Methods

Every business reports its income over a fixed twelve-month stretch called a tax year, and you pick that stretch when you start. There are two flavors. A calendar tax year runs January 1 through December 31. A fiscal tax year ends on the last day of any month other than December, so a business could run from July 1 through June 30, or from October 1 through September 30, whatever fits its operation. The rules for both live in IRS Publication 538, which covers accounting periods and methods in plain detail.

Most individuals and most small businesses land on the calendar year, and there is a practical reason for that. If you keep your books on a calendar year, or if you keep no formal books at all, the IRS expects you to file on a calendar year. A sole proprietor who reports business income on Schedule C of the Form 1040 is almost always on a calendar year, because the personal return that the business income flows into is itself a calendar-year return. Lining the two up keeps everything simple. You close the books December 31, you file in the spring, and you are done.

So when would a business want a fiscal year instead? Usually it comes down to the natural rhythm of the business. A retailer that does most of its volume in December might not want to slam its books shut at the busiest moment of the year. A school or a seasonal operation that winds down in the summer might find a June 30 year-end cleaner, because the slow period is the right time to count inventory, settle accounts, and close the books. The point of a fiscal year is to end the reporting period when the business is naturally quiet, so the year-end work is not a fire drill on top of peak season.

There is a wrinkle for pass-through entities. Partnerships and S corporations face restrictions on the tax year they can adopt, because the IRS does not want owners deferring tax by running the business on one year and themselves on another. A partnership generally has to match the tax year of its owners, and an S corporation is generally pushed onto a calendar year unless it can show a business purpose for something else. So while a fiscal year is an option on paper, the practical menu narrows fast once you account for the entity type and the owners behind it.

The first tax year is also a bit different from the ones that follow. A new business often has a short first year, because it did not start operating on January 1. If you open the doors in April and run a calendar year, your first tax year covers April through December, not a full twelve months. That short period is normal, you report it as is, and the next year picks up the full twelve-month cycle. The short first year is not a fiscal year, it is just a partial calendar year that happens because the business was born mid-year.

The choice matters more than it looks. Once you adopt a tax year, you are committed to it, and switching later is not a casual paperwork change. It affects when income gets counted, when deductions land, and how your filing deadlines fall across the calendar. We walk new business owners through this decision when we set up the entity, because picking the wrong year-end and then trying to unwind it is far more painful than getting it right the first time. If you want a second look at which year-end fits your operation, that is part of our tax strategy consulting work, and we keep the books aligned to whatever year you choose through our bookkeeping service so the close at year-end is clean.

A new business adopts its tax year by the simple act of filing its first return on that year. You do not file a separate application to pick a calendar year. You just file the first Form 1040 with the business income on Schedule C, or the first entity return, using the year-end you intend to keep, and that first filing locks it in. The IRS lays out this adoption rule in Publication 538. So in practice the decision gets made the moment that first return goes out the door, which is one more reason to think it through before you file rather than after.

If you want a fiscal year right out of the gate, you generally adopt it the same way, by filing that first return on the fiscal year and keeping books that match. The catch is the restrictions tied to the entity. A sole proprietor has the most freedom, but even there the calendar year is the default expectation if you keep no separate books. Partnerships and S corporations face tighter rules and often have to take a required tax year unless they can justify something else. So the freedom to adopt a fiscal year is real for some businesses and almost nonexistent for others, depending on how the business is structured.

Now the harder part. Once you have adopted a tax year, changing it later generally needs IRS approval, and the form for that is Form 1128, the Application to Adopt, Change, or Retain a Tax Year. You do not get to switch from a calendar year to a June 30 fiscal year just because it would suit you better this season. You file Form 1128, you state the reason for the change, and the IRS decides whether to grant it. Some changes qualify for automatic approval if you meet the conditions spelled out in the rules. Others require you to request a ruling and show a real business purpose, not just a tax-timing advantage.

Why is the IRS so protective of your tax year? Because a year-end change can shift income from one tax period to another, and that can defer tax. If a business could freely move its year-end around, it could push income into a later year or pull deductions into an earlier one to game the timing. The approval requirement is the guardrail. The IRS wants to see that you are changing the year for a legitimate operational reason, like aligning with a natural business cycle or matching a parent company, rather than just chasing a one-time deferral.

A change of tax year usually creates a short tax year in the transition. If you move from a December 31 year-end to a June 30 year-end, you end up with a stub period covering the months between the old close and the new one. That short period gets its own return, and because it covers fewer than twelve months, the income on it may need to be annualized for rate purposes in some cases. This is the kind of mechanical detail that trips people up, because the short-year return does not behave like a normal full-year filing, and the math has to be handled carefully.

The takeaway is to get the year-end right at the start. Adopting a tax year is free and automatic on the first return. Changing it later means an application, a justification, IRS approval, and a messy short-year return in the middle. We handle the Form 1128 process when a client has a genuine reason to change, but more often the better answer is to choose well on day one. If you are setting up a new entity and are not sure which year-end serves you best, we map that out as part of our tax strategy consulting service, and once the year is set we keep the records on that cycle through our bookkeeping work so every close lands on the right date.

The accounting method is the rule that decides when income and expenses hit your tax return, and the two main choices are the cash method and the accrual method. They can produce very different taxable income for the exact same business in the exact same year, which is why the choice is not just bookkeeping trivia. IRS Publication 538 covers both in depth, and the core distinction comes down to one word: timing.

The cash method is the one most people already think in. Under the cash method, you report income when you actually receive it and you deduct expenses when you actually pay them. Money comes in, you count it. Money goes out, you deduct it. A freelancer who sends an invoice in December but does not get paid until January reports that income in January, the year the check arrived, not December when the work was billed. Same on the expense side. If you pay a vendor in January, the deduction lands in January. The cash method tracks the movement of money, which makes it easy to follow and easy to keep on a simple set of books.

The accrual method works on a different clock. Under the accrual method, you report income when you earn it and you deduct expenses when you incur them, regardless of when the cash actually changes hands. That same freelancer on the accrual method would report the December invoice as December income, because the work was done and the income was earned that month, even though the check did not arrive until the following year. Expenses follow the same logic. If you receive goods or services in December and get billed for them, you deduct the cost in December when the obligation arose, not in January when you write the check. The accrual method matches income and expenses to the period that generated them, which is why it gives a truer picture of how a business actually performed in a given year.

The practical effect shows up at year-end. Picture a consulting business that finishes a big project in late December, bills 50,000 dollars, and collects in January. On the cash method, that 50,000 dollars is next year income, and the business owes no tax on it this year. On the accrual method, that 50,000 dollars is this year income, taxed this year, even though the cash is not in the bank yet. Now flip it to expenses. A business that runs up 20,000 dollars of bills in December but pays them in January deducts that amount this year under accrual, but not until next year under cash. The method literally moves income and deductions across the year-end line.

Neither method is better in the abstract. The cash method is simpler and tends to let a growing business defer tax, because you are not taxed on money you have not collected yet. The accrual method gives a more accurate read of profitability and is required for many larger businesses and for businesses that carry inventory. A small service business with no inventory usually finds the cash method cleaner and friendlier on cash flow. A business with receivables, payables, and stock on the shelves often has to use accrual whether it wants to or not.

One rule cuts across both methods and surprises people. You generally have to use the same method consistently from year to year. You cannot run cash one year because it defers income, then flip to accrual the next year because that year accrual is better, then flip back. Consistency is the price of the system, and once you pick a method you stick with it unless you go through the formal change process. We help business owners pick the method that fits how the business actually runs and how the cash moves, which is part of our tax strategy consulting work, and we set up the books on that method through our bookkeeping service so the records support whichever method you are on.

The cash method is the friendlier of the two for most small operations, and the good news is that most small businesses can use it. The IRS sets a gross-receipts test, and a business with average annual gross receipts under the threshold generally qualifies to use the cash method, even if it has inventory. The exact dollar figure adjusts over time for inflation, so check the current-year number in Publication 538 before you rely on it. The point is that the cash method is not some special privilege reserved for tiny businesses. A solid share of small and mid-sized businesses fall under the threshold and can choose it.

Some businesses do not get the choice. Larger businesses with average gross receipts above the threshold are generally pushed onto the accrual method. C corporations and partnerships with a C corporation partner above the receipts test usually have to use accrual. And historically, businesses that carry significant inventory leaned toward accrual, though the rules for small businesses under the gross-receipts threshold have loosened that requirement, letting many smaller inventory-carrying businesses stay on the cash method or a simplified version of it. So the line runs roughly like this: under the threshold, you generally pick what works for you, and over the threshold, accrual is often mandatory.

Even on the cash method, you cannot simply sit on income to push it into next year, and that is where the constructive receipt rule comes in. Constructive receipt says you are taxed on income that is made available to you, even if you have not physically taken it yet. The classic example is a check. If a client mails you a check that arrives in your mailbox on December 30, you have constructively received that income in December, even if you do not deposit it or even open the envelope until January. The income was available to you, you had control over it, so the IRS treats it as received the moment it was within your reach.

The rule shuts down a tempting little game. Without it, a cash-method business could just delay cashing checks at year-end, leave December payments sitting in a drawer, and report all of it the following year to defer tax. Constructive receipt blocks that. If the money was credited to your account, set apart for you, or otherwise made available so that you could draw on it, it counts as income then, regardless of whether you actually grabbed it. You cannot turn away income that is yours for the taking and pretend you did not earn it yet.

There are limits to the rule, and they matter. Constructive receipt requires that the income actually be available to you without substantial restriction. If a payment is genuinely not yet payable, or if there is a real condition you have not met, you have not constructively received it. A bonus that the company has not yet declared, or a payment contingent on something that has not happened, is not constructively received just because it might be coming. The test is control and availability. If you can reach out and take the money, it is yours for tax purposes. If a real barrier stands between you and the cash, it is not.

This is why year-end timing on the cash method is more subtle than it first appears. You do have some control over the timing of income, because you can choose when to send invoices and when to render services. But once a payment is available to you, the clock has run, and trying to defer it by ignoring the check does not work. We coach cash-method clients on the legitimate timing moves that do work and steer them away from the ones that do not, which is part of how we approach our individual tax return preparation, and we keep the books accurate enough to apply constructive receipt correctly through our bookkeeping work.

Switching from one accounting method to another is not something you do quietly on your own return. Changing an accounting method generally requires IRS consent, and you request that consent on Form 3115, the Application for Change in Accounting Method. If a business wants to move from the cash method to the accrual method, or the other way around, Form 3115 is the vehicle, and the procedure is laid out in Publication 538. You do not just start reporting differently and hope the IRS goes along with it. You file the application and follow the process.

There are two broad lanes for a method change. Some changes qualify for automatic consent, meaning if your change is on the IRS list of approved automatic changes and you meet the conditions, you file Form 3115 and you do not need to wait for a separate ruling. Other changes are non-automatic and require advance consent, where you file the form, pay a user fee, and wait for the IRS to approve before you can make the change. A move from accrual to cash for a small business that now qualifies under the gross-receipts threshold is often an automatic change, which makes it far easier than it sounds.

The trickiest piece of a method change is the section 481 adjustment, and it exists to prevent income from being counted twice or skipped entirely. When you switch methods, some items that were already reported under the old method might get reported again under the new one, or some items might fall through the cracks and never get reported at all. The section 481 adjustment is a one-time true-up that catches those items. It calculates the net effect of the change as if you had always been on the new method, and then layers that adjustment onto your income. If the adjustment increases your income, you generally get to spread it over four years. If it decreases your income, you usually take it all in one year.

Run a quick example. Say a cash-method business has 30,000 dollars of receivables it has not yet been taxed on, because under cash you do not count income until you collect it. The business switches to accrual, where that 30,000 dollars would have already been income. The section 481 adjustment captures that 30,000 dollars so it gets taxed under the new method, and because it raises income, the business spreads it across four years rather than swallowing the whole thing at once. The adjustment is what keeps the switch honest, making sure no income disappears in the gap between the two methods.

Now the core reason any of this matters: the choice of method affects the timing of your tax. The method does not change the total amount of income your business earns over its life. What it changes is which year that income lands in, and that timing is worth real money. Deferring income to a later year keeps cash in your hands longer, and a dollar of tax paid next year is cheaper than a dollar paid this year. Accelerating a deduction into the current year lowers this year tax bill. The method you use sets the rhythm of when income and deductions hit, and over the life of a business that rhythm adds up.

That is also why you cannot flip methods at will. If you could switch every year to whichever method produced the lowest tax, the timing advantage would be infinite, so the IRS gates the change behind Form 3115 and the section 481 adjustment. A method change is a real decision with a real process, not a year-to-year toggle. We handle Form 3115 filings for clients who have outgrown the cash method or who now qualify to drop back to it, and we model the section 481 adjustment before filing so there are no surprises, which is the heart of our tax strategy consulting service. We pair that with clean records through our bookkeeping work, because a method change is only as accurate as the books behind it.