Sales tax on an invoice: 5 steps to round and add it

Key takeaways

• check whether each item and each charge is taxable before running any math on that line.
• write the price, the rate and the unrounded result on the same line so each figure can be traced.
• pick one rounding point and apply it the same way to every invoice you send.
• give a taxable delivery charge its own line and add it to the taxable amount.
• show the tax amount on the bill and keep a copy of the final invoice with your records.

Why invoice sales tax goes wrong

Invoice sales tax usually goes wrong in the decisions made before any arithmetic happens. A line gets billed without anyone asking whether the item is taxable, or a delivery fee gets added without its own check. The multiplication and rounding are quick once those decisions are made, which is why they are easy to skip when an invoice is prepared in a hurry.

Three checks belong on every line before the total is final: whether the item is taxable, which rate applies, and whether a charge such as delivery belongs in the taxable amount. Missing any one of them changes the figure the buyer is asked to pay, so each check needs a visible place on the working sheet.

Separate columns for each figure show where it came from, so a mistake can be found before the invoice goes out.

The table below gives one sentence from each of three sources. Each source covers a different part of the job, so read the full page before copying any method from it.

The Texas page includes worked examples, the New York page points to a list of items, and the Odoo page covers setting payment terms on customer invoices.

Step 1: Confirm the item is taxable

Before any amount is calculated, mark each line on the invoice as taxable or not taxable. Keep that mark with the item in your price list, so the same check is available each time the item is billed and a new invoice does not depend on memory.

The Texas page starts from a taxable item, which is why the taxability check comes first in this guide. According to Texas Comptroller of Public Accounts, "EXAMPLE: You sell a taxable item for $250 and must charge 8.25 percent tax."

Those two figures come from one Texas example, so treat them as an illustration of the arithmetic and not as a rate for your own sale. The rate that applies to your sale is the one you check for your state and your transaction.

When you check taxability, note the state where the sale is made and whether the buyer has given you any paperwork. The New York exemption page, for example, points readers to Publication 750, A Guide to Sales Tax in New York State, for the list of items and services that may be purchased tax-free without an exemption certificate, according to New York State Department of Taxation and Finance.

Before marking an item as tax-free, read the state's own list for that item.

If the same item is sold in more than one state, keep a separate taxability mark for each state rather than one mark for the item.

Keep a short note beside each taxability mark, such as the date you checked and the source you used. A note like that lets a bookkeeper see the reason for the mark without asking the person who set up the item.

Step 2: Multiply price by the rate

Multiply the taxable price by the tax rate. In the Texas example, according to Texas Comptroller of Public Accounts, "The tax rate multiplied by the sales price equals $20.625."

The example uses 8.25 percent, so use the rate that applies to the sale in front of you rather than copying that number.

Check the multiplication on a calculator or a spreadsheet cell rather than in your head, and write the calculation down exactly as it was run. A written calculation can be checked later, while a figure produced from memory cannot.

Keep the result unrounded until the rounding step. That way the rounding in the next step is the only change made to the figure, and a reviewer can compare the two values directly. Record the price, the rate and the unrounded result on the same line of your working sheet, so the arithmetic can be followed without redoing it.

If a line mixes taxable and non-taxable amounts, split it into two lines before multiplying. Then only the taxable portion goes into the rate calculation, and the non-taxable portion stays out of it.

Use one source for each rate and write its date beside the rate on your working sheet. When a rate changes, the dated note shows which invoices were calculated with the earlier figure, which is easier to review than trying to recall it later.

Step 3: Round the third decimal

Round using the rule that applies where the sale is taxed (the Texas example rounds at the third decimal place). According to Texas Comptroller of Public Accounts, "Because the third decimal place is a five, round up and charge $20.63."

The rounding rule comes from a Texas example. It does not carry over to other states, so check the rounding rule that applies where the sale is taxed before copying the method.

Use one rounding method on every invoice, so the figures stay consistent from bill to bill. Store the unrounded figure in one column and the rounded tax amount in the next, so both values are visible when you review an invoice.

Test your method on a figure that ends in five at the third decimal place, as the Texas example does. Running that test in your spreadsheet or invoice tool shows how it handles the same kind of figure before a real bill depends on it.

Note the rounding method at the top of your working sheet. A reviewer who sees the method written there does not have to guess how the rounded figure was reached.

Keep the rounded tax in the same format on every invoice, with the same number of decimal places, so each total can be checked against the working sheet line by line.

Step 4: Add delivery charges

Delivery is a separate charge on the invoice, so it needs its own taxability check. The Texas sofa example starts with the fee itself. According to Texas Comptroller of Public Accounts, "You agree to deliver the sofa and charge a separate fee of $50 for delivery."

The same page then answers the taxability question for that sofa case. According to Texas Comptroller of Public Accounts, "Because the sale of the sofa is taxable, the $50 delivery charge is also taxable."

That answer applies to the Texas sofa case. Check your own state's rule before treating delivery the same way on another invoice, and confirm that the item sold alongside the delivery is itself taxable, since the Texas answer rests on the sofa sale being taxable.

The Texas page also gives a separate example for a buyer who provides a certificate, involving a sofa sale with a delivery charge. The FAQ below covers it.

Give delivery its own line on the invoice, with its own price. A separate line makes the taxable status of the fee visible on the page, and it keeps the fee out of the item's price.

Run the taxability check for the delivery line separately from the item line, even when both sit on the same invoice.

Step 5: State the tax on the bill

Show the tax as its own line on the invoice, with the rounded amount visible to the buyer. Use the same label on every bill so a buyer finds the tax in the same place each time.

The Texas FAQ asks, according to Texas Comptroller of Public Accounts, "Am I required to separately state the sales tax amount to my customers?" Check your state's rule before you decide how to show the tax.

The Texas FAQ's t-shirt example pairs an $18.48 price with $1.52 in tax, according to Texas Comptroller of Public Accounts. That pairing is a layout you can copy when you list the price and the tax as separate figures.

Odoo's documentation covers setting specific payment terms on a customer invoice, according to Odoo. Keep the payment terms and the tax line on the same page so a buyer reads both before paying. For how due dates are set, see Invoice payment schedules: 4 tools for due date setup.

Save a copy of the final invoice with the tax figure on it, so the amount you billed can be found later. Compare that figure with the rounded amount on your working sheet from the rounding step before the invoice goes out. To match the payment to the invoice afterwards, see Reconcile bank statements in software: 4 matching steps.

Illustrative example: tax on an item and its delivery

Assume a 10 percent rate for this arithmetic only. A taxable item sells for 500 and a taxable delivery charge is 50. The item carries tax of 50 and the delivery carries tax of 5. Both results are whole amounts, so no rounding is needed, and the tax line on the bill shows 55.

Next step: Run your next invoice through the five steps and check the rounded tax figure.

Related guides: Sales tax on invoices: 6 state rules to check · Deposit invoice: 4 steps to split the remaining balance · Deposits and partial payments in 5 invoice tools.

FAQ

How do I round sales tax?

Use one rounding rule for the sale and apply it the same way on each invoice. Check the rule that applies in your own state, and keep the unrounded figure beside the rounded one on your working sheet.

Is delivery taxable?

Delivery can be taxable: in the Texas sofa example, according to Texas Comptroller of Public Accounts, a delivery charge is taxable when the sofa sale itself is taxable. Check your state's rule before treating another delivery fee the same way.

What if the buyer gives a resale certificate?

The Texas page covers that case in a separate example, which involves a $500 sofa and a $50 delivery charge. According to Texas Comptroller of Public Accounts, the customer in that example gives a resale or exemption certificate. Check the certificate rules in your state before you change the bill.

Are some items tax-free in New York?

Some items and services may be purchased tax-free without an exemption certificate, according to New York State Department of Taxation and Finance. Check Publication 750 before marking any New York item as tax-free, and note on your working sheet which item you checked.