If you redeem the certificate before its maturity date, the bank will apply the issuance's terms and conditions, and the interest will usually be recalculated, possibly with a deduction for any previously paid interest.
Key points
Therefore, the amount you receive is not necessarily the original certificate plus all interest accrued up to the date of redemption.
Before proceeding, request an actual redemption number from the bank for today's date and check the net amount after all adjustments.
The figures, fees and limits in this answer vary by bank and change over time — confirm them with your bank or the official source before acting.