Intresting question about forever stamps what value do they have in terms of postage value?

Question

lets say you purchased a forever stamp (right before this new one) for 41C. Now it's obviously 42C. Lets say later on it becomes 45C (it will increase sooner or later). So lats say your paying for your package, but you are aloud to use postage for payment. So when sticking those postages to pay for a package (at USPS) will they calculate your payment in the old value of postage (the amount you paid for) or the new value (the amount it costs then to buy a forever stamp).

P.S. Please include how you know the answer to your question. I don't want people just guessing the answer, and saying what they think the rules are.

Answer 1

The forever stamp holds the value of a current first class stamp, no atter at what price you purchased it.  So if you have a ton of them, you can save some postage money.  The source is the USPS--they explained it when the forever stamp came out, hoping to sell a lot of them.

Answer 2

"The value of the Forever Stamp is the domestic First-Class Mail letter price in effect on the day of use."

Answer 3

A Forever stamp is good for whatever the prevailing rate for mailing one ounce by first class mail is. So if it goes up to 45 cents, you can use one, and the Post Office will deliver the letter for you. If it goes up to $3.27, you can still use it (Unless they change their minds by then). This isn't a guess, this is the definition of the stamp.

Answer 4

It's called a forever stamp for a reason. It hold the value of the current postage cost. It's kind of common sense. Plus, I'm sure you can always go ask your post office. You can also just try the USPS website.