If, after all debts and liabilities have been paid, any funds remain on hand which have been collected under the original assessment or any funds are subsequently collected through redemptions from any sale for any delinquent call on the original assessment, such funds shall, unless distributed to landowners pursuant to Section 46675, be credited pro rata to the respective tracts of land in the district on the assessment roll for the original assessment according to the rate of assessment per acre established in the original assessment and thereafter shall be applied on account for the benefit of the tracts of land against any call on any assessment levied upon the tracts through proceedings authorized under this article.