The FIFO method, short for First In, First Out, is one of the most common ways small businesses value inventory. After helping dozens of self-employed business owners clean up their books, I have seen firsthand how choosing the right inventory costing method can change both your tax bill and the story your financials tell.
This guide walks through exactly how the FIFO method works, when it makes sense, when it does not, and how to calculate it on your own products. If you run a retail, manufacturing, or ecommerce operation, understanding the FIFO method is one of the highest-leverage things you can do before tax season.
What is the FIFO method?
The FIFO method assumes that the first units you purchase or produce are the first ones you sell. When you record a sale, the cost of goods sold comes off the oldest layer of inventory on your books, and the units you have left are valued at the cost of the newest purchases.
This matters because inventory costs usually change over time. If prices rise, your most recent purchases cost more than the older ones. FIFO leaves those more expensive units on your balance sheet, which tends to make ending inventory look higher and gross profit look stronger during inflation.
A quick FIFO example
Say you run a small coffee roaster. In January you buy 100 pounds of green coffee at $5 per pound, then in March you buy another 100 pounds at $7 per pound. You sell 120 pounds over the quarter.
Under the FIFO method, your cost of goods sold comes off the January layer first. That is 100 pounds at $5 and 20 pounds at $7, for a total COGS of $640. Your remaining 80 pounds are valued at $7 each, or $560 of ending inventory.
Why small businesses use the FIFO method
In my experience, self-employed owners gravitate toward the FIFO method for three reasons. It is intuitive, it matches physical flow in most businesses, and it produces a clean story in financial statements.
Matching the physical flow is the biggest one. If you sell perishable or dated items such as food, medicine, or cosmetics, you are selling the oldest units first in real life. Using FIFO in your accounting simply mirrors reality.
FIFO method advantages
The main advantages of the FIFO method are clear financial reporting and straightforward audit trails. Your balance sheet shows inventory close to current market value, which is helpful when you apply for a loan or pitch to an investor.
FIFO also tends to produce higher reported profit during rising-cost periods, because older, cheaper units roll into cost of goods sold. That can help with financing conversations, though it does mean a higher tax bill in those same periods.
FIFO method disadvantages
The same feature that makes FIFO attractive to lenders can hurt you at tax time. When prices rise and your COGS comes from older, cheaper inventory, your profit margin on paper looks bigger, and you pay income tax on that higher profit.
FIFO also requires disciplined recordkeeping. You have to track each purchase layer with its date and cost, and pull from the oldest layer every time you record a sale. If your records are messy, FIFO is harder to reconcile than a simpler weighted-average system.
FIFO vs LIFO method
The FIFO method is often compared to its opposite, LIFO, which stands for Last In, First Out. Under LIFO, the most recent purchases hit cost of goods sold first, which can lower taxable income when prices are rising.
For a deeper comparison, see our LIFO method guide. One critical point: LIFO is allowed under US GAAP but not under international accounting standards, so if you ever plan to work with international investors or partners, FIFO is the safer default.
FIFO method vs weighted average
Weighted-average costing takes all units in inventory, adds up their total cost, and divides by the total units. Every sale uses that blended cost instead of picking from a specific purchase layer.
Weighted average is easier to run, but it hides pricing trends inside a single number. The FIFO method gives you more visibility into how your input costs are evolving, which is useful when you need to reprice your own products.
How to calculate the FIFO method step by step
Here is the simple four-step process I walk clients through.
First, list every purchase as a separate layer with the date, quantity, and unit cost. Second, record each sale and pull the units needed from the oldest layer first. Third, continue pulling from subsequent layers as older ones are exhausted. Fourth, at period end, multiply your remaining units by the unit cost of the most recent layers to get ending inventory value.
If you use accounting software such as QuickBooks or Xero, you can enable FIFO tracking in the inventory settings. The software handles the math once you enter each purchase and sale.
Tax implications of the FIFO method
FIFO affects both cost of goods sold and taxable income. During inflation, FIFO generally produces higher taxable profit than LIFO or weighted average, which means a higher current-year tax bill.
The IRS requires consistency: once you pick an inventory method, you generally must stick with it unless you file Form 3115 to change. Review the current guidance on the IRS website or talk to a CPA before switching methods.
When the FIFO method is the right choice
The FIFO method is usually the right choice if you sell perishable goods, if your inventory costs are stable or falling, or if you want the cleanest possible financial statements for lenders and investors. It also lines up with physical flow for most retail operations.
If you are just getting organized, start with our self-employed bookkeeping guide before layering in inventory accounting. Clean books come first, then inventory method.
When to avoid the FIFO method
Avoid the FIFO method if your product costs are rising quickly and you need to reduce taxable income in the near term. LIFO or weighted average may give you a better tax outcome, though you should model both before committing.
Also think twice before using FIFO if your recordkeeping is weak. The method rewards clean, layered purchase data and punishes missing receipts.
Common mistakes with the FIFO method
The most common mistake I see is mixing personal and business inventory purchases, which makes it impossible to identify purchase layers. Keep a separate business account and every receipt tagged to an inventory layer.
The second common mistake is forgetting about shipping, duty, and handling costs. Those costs are part of your inventory layer under the FIFO method, not period expenses.
FIFO method and ecommerce sellers
For Amazon, Shopify, and Etsy sellers, the FIFO method pairs well with platform reports that already timestamp every purchase. Export your purchase history, group by SKU, and use the layers to price your sales.
If you sell across multiple channels, reconcile purchases against a single inventory ledger at least monthly. Otherwise your FIFO layers drift out of sync and your COGS becomes unreliable.
Frequently asked questions about the FIFO method
What is the FIFO method in simple terms?
The FIFO method is an inventory accounting approach that assumes the oldest units you bought or produced are the first ones sold. Your cost of goods sold reflects the cost of older inventory, while your remaining inventory is valued at the cost of newer purchases.
Is the FIFO method allowed for tax purposes?
Yes, the IRS allows the FIFO method for tax purposes and it is one of the most widely used inventory methods in the United States. You have to apply it consistently and disclose your method on your tax return schedule for inventory.
Why do many businesses prefer the FIFO method?
Many businesses prefer the FIFO method because it matches the way physical inventory typically moves, produces a cleaner balance sheet in inflationary periods, and is accepted under both US GAAP and international standards. It is also easier to explain to lenders and investors.
What is the difference between FIFO and LIFO?
FIFO assumes the oldest inventory is sold first, while LIFO assumes the newest inventory is sold first. During inflation, FIFO reports higher profit and higher inventory value, while LIFO reports lower profit and a lower tax bill but a weaker looking balance sheet.
Does the FIFO method increase taxes?
The FIFO method can increase taxes during periods of rising prices because older, lower-cost inventory hits cost of goods sold, leaving more profit on the books. In periods of falling prices, the opposite is true and FIFO can actually lower your tax bill.
Can I change from FIFO to another inventory method?
Yes, but the IRS requires you to file Form 3115 to request a change in accounting method. Most small business owners go through a CPA for this filing because the change affects prior-year comparability and may trigger adjustments.
Is FIFO or weighted average better for small businesses?
For most small businesses, the FIFO method is a better default because it mirrors physical flow and gives investors a clearer view of current inventory value. Weighted average is simpler to calculate but hides cost trends inside a single blended number.
Does FIFO apply to service businesses?
The FIFO method is designed for businesses that hold physical inventory, so it rarely applies to pure service businesses. If a service business also resells products, such as a salon that sells hair care products, FIFO can be used for that product inventory alone.
