There are many types of bass keys on accordion. Any column may be assigned to different kind of basses. Rows includes basses related to the respective tone. Accordion bass tones are discussed in detail under the 'Accordion' section.

The basic bass keys are the first type, located in the second column from the left side. They are played by the left arm's ring finger.

Interval between the basic and respective auxiliary bass key is three tones. Above mentioned two types of bass keys are single bass keys. Pressing such bass keys results in sounding of a single tone.

In the rest of columns there are bass keys used to play chords. Pressing such kind of bass key provides simultaneous sounding of the many tones different in pitch, i.e. the chords.

The basic chords on the accordion basses are major, minor and seventh chords.

Major is found in the third column. Minor is located in the forth column and seventh chord in the fifth one. Minor chords and seventh chords are played by the index finger, and major chords are played by the middle finger of one's left arm.