Imagine buying a 12-month gym membership and being told it is actually only valid for 11 months: you'll still be a member for the last month but they won't let you in.
As if you would stand for that.
But that's what happens when you get a passport, which is effectively useless for the last six months of its life, with so many countries refusing you entry.
Many require at least six months' validity, some require at least three months, yet some are happy to let you in so long as you get home before it runs out.
A friend of mine who had to travel overseas for a family emergency had a terrible time trying to book a flight, with less than six months left on her passport.
Airlines gave her travel agent conflicting stories about passport requirements, limiting her choice of airline and flights.
I've asked many in the travel industry but no one has been able to answer the question of why we need extra time on our passport, especially if we're only going for a few days.
Travel plans do sometimes go astray, but not generally by six months – and surely those situations could be managed.
The Australian government is not the offender; all Australian passports are valid until the day they expire and overseas visitors do not need extra validity on their passport to come to our country.
Our government does, however, collect more revenue when we have to renew our passports early.
A spokesman for the Department of Foreign Affairs and Trade says it is not possible to add the "lost" six months from the original passport onto the next one because 10 years is the maximum passport validity recommended by the International Civil Aviation Organisation.
So, when we pay $244 for a passport, we're effectively flushing $12 down the loo.
Don't get caught
The chief executive of the Australian Federation of Travel Agents, Jayson Westbury, says that while the obligation for checking validity ultimately rests with the passport holder, it is standard for travel agents to check such details.
Problems arise when people book part of their trip with an agent and part of it direct, or book various sectors of their trip independently.
"You may have a valid passport for your first hop, but not your second hop," Westbury says.
"It is reasonable to expect that an agent who does all the booking would ensure the passport is valid for everything the traveller is doing, to the best of their knowledge."
Qantas says it also checks the validity of passports as part of its processes.
"Where we have technical interaction with border agencies through Advance Passenger Processing, the system will pick up the expiry date and not authorise the customer to be uplifted," a spokeswoman says.
Qantas says airlines are required to check documents and are often held liable for transporting passengers with invalid documentation.
"Where a country determines that a passenger is ineligible to enter the country, the airline is expected to return the passenger to his home country or where he came from," says the spokeswoman.
How to check
A useful website is visalink.com.au, which allows you to search by country and the purpose of your visit for information including visas and passport validity.
Another good site is doineedavisafor.com, which provides a basic answer with a link to the relevant website.
You might need to click on the "translate" button at the top of your web browser to get that site in English, but these links give you the most authoritative source of information for each country.
In a hurry?
The Australian government offers a pretty efficient passport service, with a commitment to getting your new passport in the post within 10 working days of receiving all the documentation.
Then again, for what you have to pay for that single document, they ought to deliver it to your door with a bunch of flowers.
If you've stuffed up or need to make an emergency trip, you can pay a priority processing fee to guarantee your passport will be ready for collection or dispatch within two working days.
This costs $108 on top of the $244 adult passport fee, so it's not something you'd want to do unless you have to.
If there's any chance you might need to travel in a hurry, dig out your passport and have a look at the expiry date.