Can I take back zakat I gave by mistake?

Charity given is not taken back

Umar ibn al-Khattab once gave a horse in charity and later saw it for sale cheaply. He asked the Prophet ﷺ whether he could buy it back. The Prophet ﷺ told him not to, even for one coin, and compared taking back one's charity to swallowing one's own vomit (Sahih al-Bukhari 1490). The strong image is deliberate: what you gave for Allah's sake is gone from your hands for good.

Common "mistakes" and what to do

• You paid more than you owed. Don't ask for the difference back. Some scholars let you count the extra toward next year's zakat; others treat it as voluntary sadaqah. Either way, you are rewarded for it. See Can I pay zakat early?
• You sent it to the wrong bank account. This isn't really giving zakat at all, so you can and should ask for it to be returned, then pay the right recipient.
• The person turned out not to be eligible (for example, they were wealthy). Scholars differ: many say your zakat still counts if you checked reasonably, while the Shafi'i school says you should recover it if possible or pay again. If the person knew it was zakat and took it anyway, you may ask for it back.
• You gave a gift and later wanted it to count as zakat. Most scholars say zakat needs the intention when you give it or set it aside, so it can't be relabelled afterwards. The Hanafi school allows a later intention while the money is still with the recipient.

Why intention matters so much

Zakat is worship, and worship depends on intention. That is why most scholars want you to know it is zakat when you hand it over, even if the recipient doesn't. See Do I have to tell the person it's zakat?

Preventing it next time

Most mistakes come from rough guessing. Work out the exact figure on your zakat date, keep a short note of what you paid and to whom, and double-check bank details before sending. See How do I calculate my zakat?