What Bulk and Periodical Mailers Need to Know about the USPS "Flat Tray" Rule

 Scott
 Postage $aver Software


Effective January 22, 2023, USPS has changed the way "flats" are prepared for Marketing Mail (bulk mail) and Periodical Class mail rates. Mailers are required to use "flat trays" (also called "tubs") instead of sacks to submit flats.

This is a "flat tray". (Yes, I know it's not flat. But it's used for flats. The flatter trays that you use for letter-sized mail are called "letter trays.")

Previously, Marketing Mail mailers have been required to use sacks (or, in some case, letter trays) for flats. Periodical Class mailers have had the option of preparing sacks using either flat trays or sacks, but are no longer allowed to use sacks. (There are some exceptions ... see below.)

Two important warnings:

• Unlike sacks, flat trays must be strapped shut, so you need to order strapping materials. (NOT provided by USPS.)
  
  
• For Periodical Class mailers who are already using flat trays, note that you must now turn the tray lids inside out so that the white side shows instead of the green side. Same goes for Marketing Mail mailers.

If you have been using sacks to send your Marketing Mail or Periodical Class mail, and the mail is not a parcel, then it is a flat.

A flat is any mail that is rectangular, flexible, and fits at least one of the following requirements, regardless of whether it is a card, envelope, or package:

• its shorter side is more than 6 1/8" but not more than 12"; or,
  
  
• its longer side is more than 11 1/2"^* but not more than 15"; or,
  
  
• for Marketing Mail, its thickness is more than 1/4" but not more than 3/4";
  
  
• for Periodical Class, its thickness is more than 1/4" but not more than 1 1/4".
  

A flat also cannot be "lumpy". In other words, its thickness may not vary more than 1/4" except within 1" of the edges.

^* Every Door Direct Mail flats have a different minimum length, but EDDM is not part of this rule change.

• Place all pieces flat in the tray, not vertically. For most mail, you will still be bundling the mail first with strapping or shrinkwrap. In that case, place the bundles so they lay flat, not vertically.
  
  
• If more than one piece can fit side-by-side when placed flat in the bottom of the tray, you should make as many side-by-side stacks as possible (while still keeping all pieces horizontal) to use as much of the tray as possible.
  
  If you are using Postage $aver to prepare your mail, it will ask you how many columns will fit in your tray, so it know how many pieces will fit. It will no longer ask for the maximum weight, as you are required to prepare a full tray before starting a new one to the same destination and sort level, unless the tray weighs more than 70 pounds.
  
  
• All pieces must have the address side facing up, and must read in the same direction.
  
  
• Similarly, when preparing bundles, all pieces must have the address side facing up, and generally must read in the same direction.
  
  However, if your piece has a thick edge (for example, a saddle-stitched booklet) such that the bundle would be much thicker on one end, you can alternate the direction of the pieces within the bundle in as many as four roughly equal groups. Note that you are only changing the horizontal direction the pieces face - all addresses must still all face up.
  
  
• All flat trays must be covered with a lid, which you can get from USPS when you pick up your trays. For Marketing Mail and Periodical Class, the lid must be flipped so that the white side is showing. (Periodical Class previously used the green side.) First Class Mail flat trays continue to use the green side as in the past.
  
  
• Each covered flat tray must be secured with two plastic straps placed tightly around the width of the tray (the shorter dimension). USPS does not provide the strapping material. Strapping kits are available at commercial office supply companies, like these from Uline or Quill. Unlike letter trays, where local trays are exempted from the strapping requirement, we do not find any exemption in USPS rules for flat trays.

In general, yes, bundling is still required.

But there are exceptions. No bundling is required for a particular tray if all of the bundles in that tray have the same destination and sort level as the tray itself.

For example, if the tray tag says it's a 3D tray going to 770, and the endorsement lines on all of the pieces say 3D 770, then no bundles are used because they are all being sorted just down to the 3-digit level. Bundling serves no purpose if it doesn't separate the mail more finely than the tray does.

But if the endorsement lines in at least one of the bundles in that tray say 5D 77005, then all pieces in the tray must be bundled, because there are enough pieces going to 77005 to be worth keeping them separate from the rest of the tray (but not enough pieces to be worth their own 77005 tray).

Also, bundles are no longer required or allowed for First Class flats. Bundles are now also optional for Marketing Mail or Periodical Class flats if the mailing has 500 pieces or less. And, effective July 15, 2025, bundling is optional for mailings of Marketing Mail barcoded flats, regardless of quantity, and for some mailings of Marketing Mail nonbarcoded flats.

But note that if bundles are optional, you may save postage by preparing the bundles. In those cases its up to you whether the hassle of bundling is worth any postage savings.

For each tray, Postage $aver figures out whether bundles are used, and shows that on the label sheets and on the Mail Preparation Instructions report.

Here are more details on the current bulk mail bundling requirements.

USPS has provided the following exceptions to the flat tray rule where sacks are still permitted.

For Periodical Class and Marketing Mail, sacks can still be used for nonpalletized flats as follows:

• residual 5-digit scheme flats entered with carrier route flats when mailed at the post office delivering that zip code (the "DDU");
  
  
• Nonbarcoded Marketing Mail carrier route flats, when mailed at the origin SCF (sectional center facility sorting center);
  
  
• 5-digit, 3-digit or SCF flats, when mailed at the origin SCF.

Note that the Periodical Class per-container charge for sacks is more than the charge for the same mail if prepared in flat trays.

For "Every Door Direct Mail" sacks can still be used.

Postage $aver Pro and Postage $aver Lite do not support the exceptions to the flat trays requirement.

Questions? Ask us and we'll do our best to answer.