Short Payments and Deductions: Handling Underpaid Invoices

Quick answer: A short payment is when a customer pays less than the invoice total without an agreed installment plan. Handle it by applying what was received, recording the gap as an open item, finding the reason, then either accepting it with a credit note or disputing it with evidence. Log every short payment invoice and its cause to prevent repeats.

A payment arrives, you go to mark the invoice paid, and the numbers do not match. Maybe $25 is missing, maybe $1,800. It is tempting either to ignore a small gap or to fire off an angry email about a big one. Neither works well. Short payments and deductions are a normal part of B2B selling, and most have an ordinary explanation. What matters is having a consistent way to sort them, recover what you are owed and stop the same issue recurring. This guide covers the causes, a step-by-step process, a worked example, wording you can use and the mistakes to avoid.

Why customers underpay invoices

Most short payments fall into a handful of groups. Knowing the group tells you who should deal with it.

Cause	Example	Usually valid?	Who resolves it
Bank or transfer fees	Intermediary bank deducts a fee from an international wire	Depends on agreed charge terms	Finance; fix payment instructions
Early payment discount	Customer takes 2% for paying within 10 days	Valid if paid within the window	Finance
Late discount	Customer takes the 2% after the window closed	Not valid under the terms	Finance, with a policy decision
Pricing difference	Invoice price differs from the purchase order price	Depends on which price was agreed	Sales and finance
Shortage or damage	Customer received 95 units instead of 100	Valid if supported by delivery evidence	Operations
Returns	Goods sent back, credit not yet issued	Usually valid once return is confirmed	Operations and finance
Promotional or rebate allowance	Retailer deducts an agreed marketing allowance	Valid if in the trade agreement	Sales
Compliance penalties	Retailer fines late delivery or wrong labeling	Only if in the agreed supplier terms	Operations and sales
Withholding tax	Customer withholds a percentage for the tax authority	Often required by law	Finance, with tax certificate
Error	Keying mistake, wrong invoice paid, duplicate credit taken	No	Finance

Withholding tax deserves a special mention because it is not really a short payment: in many countries the customer must pay part of the invoice to the tax authority on your behalf. Our guide to withholding tax on invoices explains how to record it and why you need the certificate.

How to handle a short payment, step by step

1. Apply the cash you received. Record the payment against the invoice so the balance shows the real shortfall. Do not leave the whole payment unapplied while you investigate. Our guide to cash application explains how to post it.
2. Log the gap as an exception. Note the invoice number, customer, amount, date and any reason code the customer gave. A simple spreadsheet works.
3. Look for the reason in what you already have. Check the remittance advice, the purchase order, delivery notes, emails and any credit notes already issued.
4. Ask the customer if the reason is missing. Be specific about amounts and invoice numbers, and ask for supporting documents for any claim.
5. Decide: valid or invalid. Compare the reason with your contract, your terms and your evidence.
6. If valid, issue a credit note. Reference the original invoice and the reason, and apply the credit to close the balance. Our credit note guide covers what to include.
7. If invalid, dispute it. Send your evidence, restate the amount due and give a payment date. Follow the process in our article on resolving an invoice dispute.
8. If uneconomic to chase, write it off under your threshold. Record the write-off with the reason and approval.
9. Fix the cause. Change payment instructions, correct pricing, improve packing or tighten your terms so the same short payment does not happen again.

Short payment worked example

Illustrative numbers for a food producer selling to a regional grocery chain. Invoice INV-2207 is for:

• 200 cases at $36.00 = $7,200.00
• Sales tax at 0% (wholesale for resale, exemption certificate on file)
• Invoice total: $7,200.00, terms 2/10 net 30

The customer pays $6,724.80 on day 8 with a remittance showing three deductions. Total shortfall: $7,200.00 − $6,724.80 = $475.20.

• Early payment discount, $144.00. 2% × $7,200.00 = $144.00. Paid on day 8, inside the 10-day window. Valid.
• Shortage, $180.00. The customer says 5 cases were missing: 5 × $36.00 = $180.00. The carrier's signed delivery note shows 200 cases received without exception. Invalid, unless the customer can show a later count.
• Promotional allowance, $151.20. The customer deducted 2.1% for a store promotion: 2.1% × $7,200.00 = $151.20. The trade agreement provides a 2.0% allowance: 2% × $7,200.00 = $144.00. Valid up to $144.00; $7.20 overclaimed.

Check: $144.00 + $180.00 + $151.20 = $475.20, which matches the shortfall.

Resolution: the producer records the $144.00 discount and issues a credit note for the $144.00 promotional allowance. That leaves $180.00 + $7.20 = $187.20 disputed. The producer sends the signed delivery note and a copy of the trade agreement, asks for $187.20 by a set date, and shows the balance on the next statement of account. Notice that the discount was valid because the customer paid within the window. Had the payment arrived on day 14, the $144.00 discount would also have been disputed under the terms.

What to say: short payment email template

Keep the tone neutral and the facts precise. For example:

Subject: Invoice INV-2207 – balance of $187.20

Hello [name], thank you for your payment of $6,724.80 received on [date] against invoice INV-2207 ($7,200.00). We have applied the 2% early payment discount ($144.00) and issued credit note CN-0310 for the 2% promotional allowance ($144.00) under our trade agreement. Two items remain: a $180.00 deduction for 5 missing cases, and $7.20 of the promotional deduction above the agreed 2%. The attached delivery note shows 200 cases signed for without exception. Please arrange payment of $187.20 by [date], or send any documents that support the shortage claim. Happy to discuss.

Preventing short payments before they happen

Make the invoice match the order

Pricing deductions usually start with a mismatch between the invoice and the purchase order. Quote the PO number, use the same item descriptions and unit prices, and itemize clearly. Build each invoice in the free invoice generator from the PO, line by line, so the totals reconcile on the customer's side too.

Be explicit about bank charges

For international customers, state who pays transfer fees and ask payers to choose the option that sends the full amount, where your agreement says they should. Our guide to invoicing international clients covers currency and fee wording.

Spell out discount windows

If you offer an early payment discount, print the exact last date and the discounted amount on the invoice. Our article on the early payment discount shows how to word it so late discounts are easy to challenge.

Keep proof of delivery

Signed delivery notes, photos at dispatch and carrier tracking records turn a shortage claim from an argument into a quick check.

Recording short payments in your books

How you record the gap depends on how it is resolved. Your accountant may use different account names, but the principles are consistent:

• While under investigation: the unpaid amount stays in accounts receivable against the original invoice. Do not move it anywhere else yet.
• Valid discount: record it as a sales discount, which reduces revenue.
• Valid allowance, shortage or return: issue a credit note. Where sales tax or VAT was charged, the credit note also reduces the tax you owe on that sale, which a plain write-off would not do.
• Bank charges you agree to absorb: record them as a bank charges expense, not as lost revenue.
• Withholding tax: record it as tax paid on your behalf, supported by the customer's certificate, rather than as a loss.
• Uncollectible balance: write it off as bad debt with documentation. Our guide to the bad debt write-off explains the steps and records to keep.

Using the right treatment matters beyond tidiness. If every gap goes into one "sundry write-offs" account, you cannot see whether you are losing money to bank fees, to pricing errors or to customers who simply take what they like.

Deductions from large retail customers

If you sell to supermarkets, big-box stores or large distributors, deductions can become a steady stream rather than an occasional surprise. Large buyers often publish supplier manuals listing fines for late deliveries, incorrect labels or missing advance shipping notices, and they usually set a deadline for disputing a deduction. Treat those manuals as part of your contract: read them before you sign, train your warehouse on the requirements and keep the evidence each requirement calls for. Review deductions by reason code every month. A rising number of compliance fines often points to one fixable operational step, such as a labeling printer or a carrier that routinely misses delivery slots.

Common mistakes with short payments and deductions

• Writing off everything small. Without a pattern review, repeat deductions become a hidden price cut.
• Editing the original invoice. Never change an issued invoice to match what was paid. Use a credit note for valid deductions and leave the invoice intact.
• Leaving the balance unapplied. If the full payment sits unapplied, the whole invoice looks unpaid and reminders go out for the wrong amount.
• Disputing without evidence. A dispute is only as strong as your delivery notes, contract and correspondence.
• Waiting too long. Many large customers have time limits for raising deduction disputes in their supplier terms. Raise yours promptly.
• Not involving operations or sales. Finance cannot fix packing errors or unclear promotions alone.

Short payment handling checklist

• Payment applied to the invoice the day it arrives; shortfall visible as an open balance.
• Exception logged with invoice number, amount, reason code and owner.
• Remittance, PO, delivery proof and contract checked before contacting the customer.
• Customer asked, in writing, for the reason and supporting documents.
• Valid deductions closed with a credit note referencing the invoice.
• Invalid deductions disputed with evidence and a payment date.
• Write-offs only below a written threshold, with approval.
• Monthly review of deduction causes by customer and reason.
• Root cause fixed: pricing, payment instructions, packing or terms.

Know your rights on unpaid balances

An unpaid short balance is, legally, usually just an unpaid invoice. In some jurisdictions you can claim statutory interest on late commercial payments. In the UK, for example, the government's guidance on late commercial payments explains the interest and fixed compensation businesses can claim. Rules differ by country and contract, so check before you add interest to a disputed amount.

Next step

Pull every open short payment from the last three months into one list and sort by reason. If one cause dominates, such as bank fees or pricing mismatches, fix that first. For more on getting paid in full and on time, browse our payments articles.