The maximum pairing bonus in an MLM binary plan is typically determined by the MLM company's compensation plan rules and structure. Here are some key points:

Binary plans allow members to sponsor two people directly under them, forming a binary or 2 x 2 matrix structure. Pairing bonuses are earned when both sides of the binary team are filled.

Companies will set a maximum percentage of sales volume or point value that can be earned as a pairing bonus. This prevents unlimited earnings and ensures financial stability.

Common maximum pairing bonuses range from 5-15% of the lesser leg's sales volume or point value. Some plans scale the percentage down as volume increases to higher levels.

The maximum is usually determined based on modeling of anticipated sales volumes and payouts to ensure the business remains profitable long-term. It depends on factors like product pricing and commission rates.

Some plans have no outright maximum but instead implement caps, tiers or reductions in the percentage paid out as sales/legs grow beyond certain thresholds.

Companies may occasionally make adjustments to the maximum pairing bonus percentage over time as their business performance warrants.