Originally Posted by NWIFlyer

It's actually 25%, but of the total distance travelled rather than of the underlying fare earning.

So if, for example, you were on a 1,000 mile trip in the lowest Economy fare bucket, O, you'd each earn 5 TPs, you would earn 250 miles as you're in a 25% earning bucket, and your partner would earn 250 miles for the earning bucket plus 25% of the 1000 mile journey length as the bonus.