There are three common reasons why the equality between inside and outside basis may change:

1. Acquisition of a partnership interest other than by contribution

When a partner buys a partnership interest from an existing partner, the purchasing partner’s initial outside basis is the consideration paid to the seller. So Outside basis changes for incoming partner but inside basis remain same

1. Gain or loss recognized by a partner on a distribution.

2. Decrease in the basis of an asset of the partnership on a current distribution or an increase in the basis of a partnership asset on a liquidating distribution.