When new postal rates are announced, many large mailers realize that their actual prices are going to be determined only after United States Postal Service officials at L’Enfant Plaza in Washington issue new regulations defining how their mail will be classified.

In early March it was just beginning to hit some mailers what the impact of rate increases announced Jan. 15 will be.

Take nonprofit magazines, says the Alliance of Nonprofit Mailers.

The increase first was supposed to be 1.966 percent, but due to some miscalculations at postal headquarters, it was lowered to about 1.4 percent.

But now that welcome news has been followed at some publications with word that their rates are going to jump much higher, says the Alliance in a March 4 report to its members.

“And the impact could be devastating,” it says.

Consumer Reports on Health is facing a 16.16 percent increase.

Consumer Reports Money Adviser is expecting a 14.03 percent increase.

Ranger Rick, a publication for children by the National Wildlife Federation, is worried about a 9.98 percent jump.

“How did this happen?” the Alliance asked.

“We do not know all the answers, but we do think there is a chance that this can be corrected,” it said.

“We believe much of it has to do with the extreme complexity of periodical pricing,” it said, noting that those factors include weight, volume, zone, editorial versus advertising content, sort level barcoding, machinability, and containerization.

Behind the confusion is a USPS drive to get more publishers to make their publications ready for the new Flats Sequencing System, which represents a huge investment to push down the costs of processing publications.

The USPS only recently announced the new rules that will affect which rates in its Jan. 15 increase will apply to various publications.

“The bottom line for many nonprofits is that prices will increase much more than average if their publications are relatively light weight and have a low percentage of advertising,” the Alliance said.

That hits publications printed by Consumer Reports, which bans advertising, especially hard, the Alliance said.

If the USPS does not waiver, it could force some of the nonprofit publications to “discontinue mailing or reduce the frequency of their publications and look elsewhere to achieve their very important missions,” it said.

Meanwhile the Alliance said it is pressing the USPS to make “a mid-course correction” and revise its proposed rates.

David Partenheimer, a spokesman for the Postal Service, told Linn’s, “We are reviewing the issues raised by the Alliance.”