For First Class, Periodicals and Marketing Mail, except for Marketing Mail non-carrier route flats, plan for a rate increase of 2% to take effect the last week of January 2020.  

For Marketing Mail non-carrier route flats plan for a 4% increase.  This is due to a directive from the PRC (Postal Regulatory Commission) that approves rates for the USPS.  They have instructed the USPS to add 2% to the increase due to this subclass not covering its costs.

There is also a risk of an additional increase due to the 10-year review of USPS rates.  The Postal Accountability and Enhancement Act (PAEA), passed by Congress in 2007, stipulated that after ten years the PRC was required to conduct a review of the ratemaking system established under PAEA, to determine if the goals of the legislation were being met. That process is now under way, which gives the PRC the power to retain or change how rates are determined.  Presently the main method for determining rate increases has been based on the CPI.  This is how the 2% increase for most mail was determined for 2020.

At this time, it is impossible to know what action the PRC may or may not take regarding this 10-rate review and when it might go into effect.  To be on the safe side you may want to have a risk to your postage budgets of 2% to take effect in July 2020.

The only other wild card is any congressional action.