Old cheque books remain valid as long as the underlying bank account is still open and active. Banks do not automatically invalidate cheques simply because they are old. However, most banks honor cheques only within a specific validity period, typically six months to one year from the date written, though this varies by country and institution. After that window, a cheque may be considered "stale-dated" and banks may refuse to process it, though some will still cash it at their discretion. The account holder can request a new cheque book from their bank, and doing so does not necessarily void older cheques if the account remains open. If you have very old blank cheques from a closed account, they are no longer valid since there is no active account to draw from. The best practice is to verify the current status with your bank directly, as their specific policies on cheque validity periods and processing old cheques can differ. For current transactions, using modern payment methods is generally more reliable than relying on potentially expired cheques.