A letter of certification — an LOC, sometimes called a kosher certificate — is the document that proves your products are certified. The symbol on your package is the consumer-facing signal; the LOC is the document your business customers actually ask for, file, and check before they buy.
If you sell business to business, the LOC is the more important of the two. A buyer will not take a photograph of your label as evidence.
What is on it
A usable letter of certification states, without ambiguity:
- The certifying agency and its symbol, with contact details a customer can actually use
- Your company and the certified facility — by address, because certification attaches to a plant, not to a brand name
- The exact products covered, listed individually, usually with the codes or SKUs your customers order by
- The designation for each product — pareve, dairy, dairy equipment, meat, fish
- Any additional standards the product meets, such as cholov yisroel, pas yisroel, yoshon, or kosher for Passover
- The expiry date
- A way to verify it independently with the agency
The product list is the part that matters most and the part most often wrong. A letter that says “products manufactured by Acme Foods” without naming them is not evidence of anything, and a careful buyer will reject it. If your customer orders by a code, that code should appear on your letter.
Who asks for it, and why it matters more than you expect
Other manufacturers. This is the big one. If your product is an ingredient in someone else’s certified product, your LOC is part of their certification file. Their agency will request it, read it, and check its date. If yours lapses, their certification is exposed — which is why an expired letter can cost you an account faster than a price increase.
Retail and distribution buyers. Many require a current certificate as part of vendor onboarding, alongside insurance and food-safety documentation. It is a checkbox, but a checkbox that stops a listing.
Co-packers and contract manufacturers, in both directions — they need yours, you need theirs.
Export customers and importers, for whom the letter is often the only credential that travels intact.
Caterers and institutional buyers, who need the designation in writing to plan menus.
How to use it as a sales asset
Most manufacturers treat the LOC as compliance paperwork and file it. The companies that get the most out of certification treat it as a sales document:
- Include the current letter in your sell sheet and your vendor onboarding pack, unprompted. It removes a step from the buyer’s process.
- Make sure the product list matches the codes your customers actually order by, not internal names.
- Send the renewed letter to your accounts proactively rather than waiting to be asked. An expired letter in a customer’s file triggers an internal flag even when you are perfectly current.
- If you carry an additional standard, make sure it is stated on the letter. A buyer searching for a cholov yisroel or yoshon supplier will not infer it.
What it does not cover
An LOC covers the products it lists, made at the facility it names, until the date it states. It does not cover:
- Products you added after it was issued
- A second facility, unless that facility is separately certified and named
- A reformulated version of a listed product — a changed ingredient or a new supplier needs review before it runs
- Any period after the expiry date, even by a day
Adding a product mid-term is routine and usually quick, because the plant is already certified and the suppliers are mostly already reviewed. Tell us early and the new item goes on the letter without disrupting anything.
Getting and keeping one
We issue your letter of certification once your products are certified, keep it current through renewal, and reissue it whenever your product list changes. You get a clear letter your customers can verify, and a coordinator who will answer a buyer’s question directly if it is faster that way.
Get a free quote, or read how to read a certificate and how long one stays valid.