I have a roll of $0.33 stamps. I also found a bunch of old stamps marked “G rate makeup stamp”. I don’t know when the “G” stamp was introduced, but the G-rate-makeup-stamp was used as the incremental value during a former postal increase. At the time the G-rate-makeup-stamp had to be worth one or two cents.
If you don’t know, first class postage went up by one cent today. So: can I use a $0.33 stamp AND the G-rate-makeup-stamp as first class postage?
According to this–
http://www.ci.imperial-beach.ca.us/USPS-stamp-values.htm
–the G-rated makeup stamp with the dove is worth 3 cents. So yes, you can go ahead and use it with the 33 cent stamps–the Post Office doesn’t mind if you overpay. 
The G Rate Makeup Stamp… is a 3 cent stamp.
Stamps are legal tender, just like money. Money doesn’t expire.
I tried that, but the post office wouldn’t let me get away with it. Apparently the non-denominated stamps labeled ‘A’ through ‘H’ were only good for the changeover period in which they were issued.
Is that why they’re labelled with letters instead of their actual value? The USPS makes 1 cent stamps all the time, you’d think they’d just give them to people when they do a switchover.
Barth They’re wrong. You’re right. Use any combo to make 34 cents and mail away.
D’oh! Evidently I’ve been duped by a know-nothing postman…and I threw all my ‘H’ stamps away after that incident. Aaargh.
Well, the postman was PARTLY right. Those “letter” stamps, which are sometimes good for a 1st class letter, are only good for a 1st class letter during that time- after that they default to their actual paid-for value. In other words, if you bought some “D” (or whatever) stamps that cost 17 cents for 1st class mail- they would be good for 1st class mail- only as long as 1st class mail is 17 cents. Afterwards, they are just 17 cents. Some folks thought they could stock up on those “letter” stamps & get 1st class postage forever from them. Not so. He might have misunderstood your query, as the above question is asked & tried over & over.
The idea with the “letter” stamps is- they ask for a 3 cent increase- but they might only get a 1 or 2 cent. So they make up the “letter” values in advance- and then put whatever value they need to it.