Cancelled Flight? You Are Probably Owed More Than a Voucher
Airlines routinely offer vouchers to passengers whose flights are cancelled, knowing that most people do not realise they have a right to cash.

When an airline cancels your flight, a customer-service agent, or a politely worded email, will often offer you a travel voucher as compensation. Many passengers accept this without question. It is a costly habit. In most jurisdictions with robust passenger-rights frameworks, you are entitled to a full cash refund for the cancelled service, and no airline has the legal authority to make a voucher your only option.
A voucher is useful to the airline and potentially useless to you. It may carry an expiry date, be non-transferable, and lock you into flying with a carrier whose reliability you now have reason to question. A cash refund, by contrast, is a cash refund. You can spend it with any airline you choose.
What You Are Generally Entitled To
Under the passenger rights rules that apply in many markets, including the EU's Regulation 261/2004, which sets the benchmark for much of the world, a cancelled flight triggers an automatic right to a full ticket refund, alternative transport to your destination, and, in many cases, additional financial compensation depending on notice given and flight distance. The compensation element is separate from the refund and may be substantial.
The airline's obligation to provide a refund exists regardless of whether the cancellation was caused by circumstances within their control. Extraordinary circumstances, such as severe weather, may reduce or eliminate the additional compensation, but they do not eliminate the refund right. Do not let an airline conflate these two separate entitlements.
How to Push Back Effectively
Refuse the voucher and request a cash refund in writing. Quote the specific regulation that applies to your journey. Give the airline a clear deadline, fourteen days is standard under EU rules, and keep a copy of every communication. If they do not comply, escalate to your national aviation authority or the relevant alternative dispute resolution body. Many countries have free, mandatory arbitration schemes for airline complaints that airlines are legally obliged to participate in.
If the refund is still not forthcoming and you paid by credit card, a chargeback for services not rendered is a legitimate parallel route. Use all available tools simultaneously.