What the letter is for
The complaint letter is usually the first thing a supplier sees: parts were found that don’t meet a requirement, here is the evidence, contain it now and answer with an 8D by these dates. A clear first notice saves a round of questions; a vague one (“parts bad, please send 8D”) gets a vague 8D back.
The template has three parts: a formal letter with a details table and a dates table, a short e-mail version for the same-day notice, and a check-before-you-send list. The fields are generic. Your own complaint process, the supply or quality agreement and any SCAR form you use come first.
What the letter must say
| Field | Why the supplier needs it |
|---|---|
| Complaint no. and subject line | The number links the letter, the supplier’s 8D and every later reply. Put it and the part number in the subject. |
| Part, delivery, lot | Part number and drawing revision, purchase order, delivery note and lot or date codes, so the supplier can find the same parts in its own stock. |
| Requirement not met | The drawing dimension, specification or clause, with value and tolerance. “Out of spec” on its own starts a week of questions. |
| What was found | Measured values or the defect seen, on which feature, and where it was found (incoming, line, field). |
| Quantities | Delivered, checked, nonconforming and suspect stock at your site. The numbers should add up. |
| Evidence | Photos, a measurement report and sample parts, or the date they will arrive. |
| Dates | Receipt and team leader, containment, D4 root cause, actions and the full 8D, each as a calendar date. |
| Contact | One named person with e-mail and phone who answers the supplier’s questions. |
Dates: containment in 24 hours, D4 by a set date
Write every due date as a calendar date, with a time for containment. “ASAP” and “soon” can’t be missed, so nobody plans for them. The template asks for:
- Receipt and 8D team leader, the same day or the next morning.
- D3 containment within 24 hours: supplier stock, WIP, parts in transit and suspect parts at your site, with quantities checked and nonconforming per location, and how the first clean delivery is marked.
- D4 root cause by a set date: occurrence and escape, each with verification data.
- D5/D6 actions and the full 8D by the dates in your quality agreement.
24 hours, 5 and 20 working days are common customer targets, not a standard. To turn them into dates, use the 8D deadline calculator.
Evidence to ask for
Say in the letter what the 8D must show, so the first answer can be complete: containment counts per location, the occurrence and escape causes with verification, trial data for the actions, and the updated PFMEA, control plan and work instructions with revisions. The supplier SCAR 8D checklist lists what a complete answer covers, and the 8D report template is a D0–D8 structure you can point the supplier to if they don’t have one.
When the supplier’s 8D comes back, check it with the free 21-item checklist and the free 8D templates.
8D Gate’s AI review is paused for now. The checklist and templates are free to use; your customer’s requirements always come first.
Short e-mail version
For the same-day notice. Copy it, replace the brackets and attach the evidence. It is also in the Word and PDF file.
Subject: Complaint [no.] – [part number] – containment due [date, time] – 8D requested
Dear [name],
today we found [nonconforming quantity] of [checked quantity] parts [part number], lot [lot], from delivery note [no.] outside the requirement [drawing dimension / spec: value and tolerance]. Measured: [values]. Photos and the measurement report are attached.
Please: (1) confirm receipt and name your 8D team leader by [date, time]; (2) contain by [date, time], within 24 hours: your stock, WIP, parts in transit and the [n] suspect parts at our site, with quantities checked and nonconforming per location and how the first clean delivery will be marked; (3) send the D4 root cause, occurrence and escape, each verified, by [date]; (4) send the full 8D report by [date].
Please quote complaint no. [no.] on every reply. If a date cannot be met, tell us before it passes.
Kind regards, [name], [function], [phone]
Weak vs strong: the same complaint
Illustrative, fictional example: a buyer notifies a stamping supplier about a bracket with a hole out of position.
| Field | Weak | Strong |
|---|---|---|
| Description | Parts out of spec, please check. | Hole position 0.4 mm outside drawing dimension 12 (±0.2 mm) on 38 of 50 parts sampled, part 55-210 rev. C, lot 2291 |
| Quantity | Many bad parts | 1,200 delivered, 50 checked, 38 nonconforming, 1,150 suspect parts held in quarantine |
| Containment | Sort ASAP | Contain by Tuesday 10:00 (24 hours): your stock, WIP, in transit and our 1,150 parts; counts per location; clean-part label on the first clean delivery |
| Root cause | Send 8D soon | D4 occurrence and escape cause, each verified, by Friday of week 1; full 8D by the date in our quality agreement |
The strong version names the requirement, gives numbers that add up and dates that can be checked. The same layout works in other sectors: a food buyer would give the lot code, best-before date and the specification limit; an electronics buyer the date code, the test that failed and the IPC class agreed on the drawing.
Common mistakes in a complaint letter
- No requirement or measured value, only “out of spec”.
- Quantities that don’t add up, or no count of the suspect stock at your own site.
- Containment asked for at the supplier only, not for parts in transit or already at your site.
- No dates, or one date for “the 8D” with nothing for containment and D4.
- Evidence promised but not sent, or sample parts not traceable to a lot.
Once the 8D comes back, check it against the free 8D checklist before you accept or reject it.
FAQ
- Is a complaint letter the same as a SCAR?
- Not quite. The letter or e-mail is the first notice: what was found, how many, and what you need by when. A SCAR is the formal request form, often with the 8D sections on it. Many buyers send both, the letter the same day and the SCAR with it or soon after. If you use a form, start from the free SCAR template.
- Does IATF 16949 or ISO 9001 prescribe a complaint letter format?
- No. Neither standard prescribes a letter or e-mail format. What matters is that the requirement, the evidence and the dates are clear, and that the dates match your supply or quality agreement and any customer-specific requirements you pass on to the supplier.
- Is 24 hours for containment a rule?
- It is a common customer target, not a standard. Some customers ask for containment the same shift, others within 48 hours. Use the dates from your quality agreement; the 8D deadline calculator works out D3, D4/D5 and D8 dates from the complaint date.
- How do I check the supplier’s 8D when it comes back?
- Go through the free 21-item 8D checklist and compare the answer with the 8D report template and the SCAR checklist. The checklist is a self-check; the decision on the 8D stays with you as the customer.
Check it before you send
When the supplier’s 8D comes back, go through the free 21-item 8D checklist.
When the supplier’s 8D comes back, check it with the free 21-item checklist and the free 8D templates.
8D Gate’s AI review is paused for now. The checklist and templates are free to use; your customer’s requirements always come first.