A service charge on a till sale is a separate amount added on top of an order's items. The base depends on how the charge is set: a percentage of the pre-tax subtotal, or a fixed amount that does not scale with the order. The four steps are: set the base, let the till calculate the charge, apply tax to the charge, and round and verify the final total.
- Set the service charge against the order subtotal before tax, not the grand total — Square's example uses a $116 subtotal at 10%, giving $11.60
- Apportioned line-item charges must sum exactly to the order's total service charge ($3.00 + $5.00 + $3.60 = $11.60 in the example)
- The service charge carries its own tax — 8% in the example — separate from the tax on the items
- Mid-sale changes trigger a fresh recalculation of the charge from the new subtotal
- Rounding can move the total by a cent or two, depending on the till's own setup
What a service charge on a till sale actually is
A service charge on a till sale is a separate amount added to an order on top of its items, and the till calculates it before it arrives at the total the customer pays. The calculation depends on what the service charge is set against — the whole order or a single line — and on the tax and calculation phases your system applies at each stage.
The details below come from Square's Order Service Charges documentation, which walks through exactly how service charges build up on an order. You can read the full example yourself at Square Developer, "Order Service Charges".
For a shop setting, the same idea applies: your till reads the order, applies the service charge at the level you configured, applies any tax the service charge carries, and lands on the total the customer sees. Staff ringing up sales should treat the service charge as a moving part of the order — it changes when the order changes — and owners should treat the service charge total on the day's report as a figure that can be checked line by line.
Step 1: Work out what the service charge is set against
The first thing to check before any sale goes through is the base your service charge is measured from. In Square's worked example, the service charge is set as 10% of the order subtotal before tax — the subtotal excluding tax, not the grand total including it.
If the charge is a fixed amount, it stays the same regardless of the order. A fixed charge of $10 is added to the order in one of Square's scenarios.
The point to check in your till setup: is your service charge configured to sit on the order level or on individual line items? Square's example covers both. One scenario adds an order-level service charge of $10 directly to the order. Another puts the charge at the order level as a percentage, then apportions it back to line items.
| How the service charge is set | Base used in the Square example | Resulting charge |
|---|---|---|
| Percentage of order subtotal | Order subtotal $116 | $11.60 total |
| Fixed amount on the order | Order-level service charge added | $10 |
The percentage case scales with the sale. The fixed case is the same amount regardless of what's on the printed slip. Knowing which of the two your till uses tells you whether a charge line should move when the order grows or shrink.
Step 2: Let the till calculate the charge from the subtotal
Once you know the base, the calculation itself is arithmetic your till should handle without staff intervention. In the Square example, the order subtotal is $116 and the service charge is 10% of it, giving $11.60.
This is the number that appears as the total service charge on the order. It is not yet the final line the customer pays if tax applies to it, but it is the figure that everything else builds from.
Square's documentation then shows how that $11.60 splits back across individual items on the order. Three line-item service charges — $3.00, $5.00, and $3.60 — add up to the same $11.60 total service charge. This apportionment matters when the printed slip shows charges for each item rather than one charge on the order total: the parts always sum to the whole.
If your till shows service charge on the slip line by line, you can check the sum quickly. Add up the individual apportioned charges. They should match the order's total service charge exactly. On a slip that shows only one charge line, compare that line against your configured rate applied to the subtotal shown above it.
Step 3: Apply tax the way your till is configured to apply it
A service charge can carry its own tax. In Square's example, the service charge applies a special service charge line-item tax of 8%. That tax sits on the service charge itself, separate from the tax on the items.
This is where totals start to look unfamiliar to staff. A printed slip might show an items subtotal, a service charge, tax on items, and tax on the service charge — four numbers rather than the usual three.
The correct check: total service charge plus the service charge tax should equal what the customer is charged beyond the taxed items. If they do not reconcile, check rounding first, then check the tax rate in the till setup.
Calculation phases also affect the outcome. Building on an order in Square's price-adjustment examples, the calculation phases you set on an order affect service charges applied to that order.
Check your till's calculation phase settings with whoever administers your system. If the phases are ordered differently from how your slip reads, the total may look unfamiliar and be worth a second look.
Step 4: Round and verify the final total
The last step is the rounding your customer actually pays. Stripe's price documentation gives a concrete case: a calculated line item amount of 0.05 × 30 = 1.5, which rounds up to 2 cents. That example sits in a pricing context rather than on a service charge line. Your own till's rounding direction depends on your till's setup, so rounding can move the total by a cent or two.
The reason this matters at the till: small charges on high-quantity lines can shift the total by a cent or two. A service charge computed from a subtotal that includes such rounding will also shift.
How to verify on a real sale:
- Take a slip after a service-charged sale.
- Find the order subtotal before tax.
- Recalculate the service charge at your configured rate from that subtotal.
- Check it against the service charge line on the slip.
- Check that apportioned line-item charges, if shown, sum to that total.
- Add service charge tax, then the items tax, and confirm the grand total.
If step 5 fails, your till is splitting the charge inconsistently. If step 4 fails by more than a cent or two, check the base and rate; a cent-level difference may come from rounding.
What your till recalculates when the order changes
Mid-sale changes are where service charges cause the most confusion. The customer adds an item, removes a bottle, swaps a size. Your till has to recalculate the charge from the new base.
ERPNext documents this behaviour for its pricing rules: the system evaluates eligible rules when an item is added or the transaction is recalculated ( Frappe, "Pricing Rule | ERPNext Documentation").
What this means at the counter: don't try to hold a previous service charge figure in your head while editing an order. Let the sale recalculate, then read the new service charge from the screen.
A practical check when editing:
- Add an item. The service charge should move up if it's percentage-based.
- Remove an item. The service charge should move down.
- Change quantity only. A percentage charge scales with the new subtotal.
- Swap an item for one at the same price. The service charge should not change.
If a change to the order doesn't move the service charge when it should, the charge may be set as a fixed amount rather than a percentage. Fixed service charges stay the same regardless of what's on the order.
Checking the owner's side of the till report
The owner reading the till report at end of day is looking at the same numbers through a different lens. The report should show service charge collected as a distinct figure, separate from sales and separate from tax.
Reconciliation routine:
- Pull the day's service charge total from the report.
- Pull the day's order subtotals.
- Apply your service charge rate to the subtotals.
- Compare your figure to the report's figure.
Small differences come from rounding at the line level. Larger differences point to a mixed setup — some sales with percentage charges, some with fixed, some with none.
If your shop runs both kinds of charge — say a percentage on some orders and a fixed charge on others — the report figure will not be a clean percentage of the day's sales. Break the report down by sale type before you conclude anything is wrong.
Common problems and what causes them
The service charge doesn't appear on some sales. Either those sales are set up with no service charge rule attached, or the rule's conditions don't match the items on those sales. Recheck which sales carry the charge and which don't.
Line-item charges don't sum to the order's service charge. In Square's example, the three apportioned line-item charges sum exactly to the total. If yours don't, the apportionment is being recalculated on different bases for different lines — worth investigating in your system's calculation order.
The total looks right but the slip lines don't add up visually. Tax on service charge is often printed after the service charge itself. Read down the slip: subtotal, service charge, service charge tax, items tax, total.
Mid-sale edits lose the service charge. The order was recalculated but the rule didn't reapply. Check whether your rule fires on recalculation as well as on item add.
Rounding pushes the total a cent or two. This is typical of how rounding can move a total by a cent or two, and the till's own rounding setup determines the direction.
What's worth checking on your own till
Your till's exact rounding rules on service charge lines, and whether your specific configuration rounds up, down, or to nearest on each line, come down to your till's own setup — worth asking your till provider directly if the cents on your slip look wrong to you.
General information, not legal or tax advice.
Related guides
Do this today
Take the last slip with a service charge on it. Find the order subtotal before tax, multiply it by your configured rate, and check your figure against the service charge line on the slip. If it's out by more than a cent or two, open your till setup and check the base and the rate.
Quick FAQ
Does the service charge use the total or the subtotal as its base? In Square's worked example it's the order subtotal before tax — $116 in that case — giving an $11.60 charge at 10%.
Can a service charge be a fixed amount instead of a percentage? Yes. Square's example also adds a $10 order-level service charge directly to an order, which stays $10 regardless of what's on the sale.
What tax applies to a service charge? In Square's example the service charge carries a special line-item tax of 8%, charged on the service charge itself.
Do line-item service charges have to add up to the order's service charge? Yes. In Square's example, three apportioned line-item charges of $3.00, $5.00, and $3.60 total exactly $11.60 — the same as the order's service charge.
What happens when an item is added mid-sale?