I forgot to take into account investment income (dividends, interest) and gifts from the government into my ma’aser calculation for last year (תש”פ) . I will pay it now. But is there some statement I can or should make so that my payment would apply to last year’s income? I did make the statement brought in the sha’arei tzedek when I accepted upon myself to pay ma’aser.
Thank you in advance!
Now that you remembered your mistake you should just give the money to tzedakah. There is no need to make any special statements, even if the money is really paying back for last year maaser money.