You can repot houseplants in winter, but it is usually best only when necessary. During winter months, many houseplants experience slower growth because of reduced daylight. Repotting during this time can place additional stress on the plant while it is already conserving energy.
However, if a problem needs immediate attention such as root rot, pest infestations, or severely compacted soil then repotting can still be the right decision. Addressing these issues early may prevent more serious damage.
If your plant is otherwise healthy, it is generally better to wait until spring, when longer days and warmer temperatures encourage active growth. Plants are much better able to recover from root disturbance during this period.
For more seasonal care advice, read Keeping Your Plants Happy Through Winter!