Whether you're saving up for a special occasion — like a honeymoon — or just an upcoming getaway, many travelers opt to save future travel funds in a dedicated bank account. For United Airlines loyalists, this process can be even simpler.

United MileagePlus account members can access a budgeting tool called United TravelBank. Let's dive into the things you'll want to know about the service, how to use it and if it's worth "saving" money in this account at all.

What is United TravelBank? How does it work?

United's TravelBank is pretty much what it sounds like — an online account designed for accumulating travel funds for future United flights. It aims to simplify United MileagePlus members’ budgeting for future personal and/or business flights.

Once the account is set up and has money in it, it syncs with both united.com or the United mobile app as a payment option.

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What to know about United TravelBank

1. You can purchase United TravelBank credits for your account

United gives MileagePlus members the opportunity to buy deposits for their own TravelBank account. However, you can only purchase TravelBank credits in one of six amounts:

$50.

$100.

$250.

$500.

$750.

$1,000.

If you want to deposit a different amount, you can do so across multiple transactions. Say you want to deposit $150. Just purchase $50 in funds and then make another purchase of $100.

The only limitation is that you can't exceed $5,000 per day per MileagePlus account, meaning that you can do at least five purchases per day.

2. United TravelBank credits are valid for five years

Does United TravelBank expire? Yes. Purchased funds are valid for five years from the date the funds are deposited into your TravelBank account. That gives you plenty of time to use the funds.

That's a much longer validity than other types of airline travel credits. For instance, when purchasing airfare on United, you generally only have 12 months from the date of purchase to use those funds for a flight. So, if you really aren't sure that you'll be able to travel in the next year, you can use the United TravelBank to stash money away for future airfare purchases.

Even with the generous expiration policy, we recommend using up your full TravelBank balance whenever possible to avoid leaving money on the table.

3. You can get United TravelBank credits by holding an IHG card

One of the unexpected ways to get United TravelBank credits is through select IHG credit cards. IHG® One Rewards Premier Credit Card and IHG® One Rewards Premier Business Credit Card customers can enroll to get up to $50 in TravelBank Cash each calendar year. Cardholders get one deposit of $25 in early January of each year and another $25 deposit in early July.

However, these funds work differently from purchased TravelBank funds. Instead of having five years of validity, you only have a little over six months to use these funds before they expire. The $25 deposited in early January expires on July 15 of the same calendar year, and the $25 funded in July will expire on Jan. 15 of the next year.

During the two-week crossover period, you could have up to $50 in active TravelBank funds from this IHG credit card benefit. That's probably not going to be enough to cover an entire flight, but at least it can save you some out-of-pocket cost on your next United flight.

Eligible cardholders can go to ihg.com/united to register to start receiving this new card benefit. You'll need to log into your IHG One Rewards account and then provide your United MileagePlus number and last name to complete registration. The terms and conditions note that it may take up to two weeks after registration before you receive your first $25 TravelBank deposit.

4. It’s possible to use credit card travel credits to fund your United TravelBank

United TravelBank purchases often code as travel expenses on your credit card bill. That means you can earn bonus points when using credit cards with a travel bonus category. And you might even be able to use credit card travel credits — such as the Chase Sapphire Reserve® $300 annual travel credit, the Citi Prestige® Card $250 air travel credit or certain other credit card incidental fee credits.

5. You can't use United TravelBank funds for other travel purchases

A major downside of the United TravelBank is that funds can only be used to book United-operated or United Express-operated flights, plus certain subscription products.

Travelers living near an airport with a strong United presence may not mind being limited to flying United. However, if Delta Air Lines, Alaska Airlines or American Airlines offers a much cheaper airfare, you won't be able to use your United TravelBank funds to purchase those flights.

Likewise, United TravelBank funds can't be used for hotels or car rental purchases.

6. The United TravelBank doesn't earn interest

Another downside of saving funds through the United TravelBank is that you won't earn interest on the saved funds. Over the past few years, interest rates have been so low that you wouldn't have missed out on much interest income by placing funds in the United TravelBank instead.

However, now that interest rates are increasing, you might be able to grow your travel funds faster by saving funds in an actual savings account rather than the United TravelBank.

How to use United TravelBank

Once you’ve added money to the TravelBank account, you can select TravelBank cash as a payment option when logged into united.com or the United app.

When you're ready to use your travel funds, just log into your United MileagePlus account and search for a paid flight. On the checkout page, select the TravelBank payment option. Then, you can then enter precisely how much of your funds you want to apply to this booking.

Note that you can only use TravelBank funds for flights priced in U.S. dollars. And unfortunately, you can't use TravelBank funds to pay taxes and fees on a MileagePlus award ticket. For cash bookings, TravelBank monies can be used to cover the ticket price, taxes and surcharges.