What should be the accounting entry at the time of placement and maturity of fixed deposit?

Placement.

DEBIT Fixed Deposit Account.
CREDIT Bank Account.

Being placement of fixed deposit.

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Maturity.

DEBIT Bank Account.
CREDIT Fixed Deposit Account

Being the maturity of a fixed deposit.

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Um, I would hope you're getting interest on that, no? in which case the second entry will include a credit to Interest Revenue. You can also accrue the interest as it's applied to your account, but there will probably be some when it matures as well.