This Allegro, often referred to as the 'Little' Piano Sonata in B-flat major K.498a, is a delightful and accessible work by Mozart. It features a spirited main theme and classic Alberti bass accompaniment.
Requires crisp articulation and a light touch to maintain its effervescent character.
Allegro in B flat (K.498a) is rated Henle level 2 of 9 — beginner repertoire, roughly ABRSM grades 2–3. In the RCM system it corresponds to about level 4.
You should be comfortable at Henle level 2 — meaning you can already play level 1–2 pieces cleanly. Learning it one level early is possible as a stretch piece, but more than that usually leads to months of frustration.
A typical performance of Allegro in B flat (K.498a) lasts about 3 minutes.
Allegro in B flat (K.498a) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.