I'm 32, and I am pegged as a teenager on a daily basis.  I still get carded for alcohol and such every time.  People ask if I am old enough to drive.  In conversation with new acquaintances (customers at work, with whom I will spend a few hours and then never see again), I am regularly told that I have so much potential, I have my whole life ahead of me, and I ought to go to college and keep learning, and work hard while I am young, it's so good that I got into this company/industry while I am young, and start investing money now while I am young, etc. 

I do not correct them, and I do not feel that I am deceiving them.  I don't talk or act like a teenager.  They are the ones who are jumping to incorrect conclusions.  My motivation to correct them would be hoping that they would stop talking down to me, and to instead treat me with respect as a peer.  Does not work that way.  Correcting them usually just leads to minor awkwardness.  Not worth it.  In the end, I don't really care what they think of me. 

Not often. I've had a lot of people assume I am like 17-18 and I let it go unless someone says something that prompts me to talk about my age.

People always seem to get my age wrong but whether or not I correct them just depends on the mood I am in and where I am at.  I guess people get it wrong so often because of my height and appearance.

People usually guess me younger; sometimes as much as 15-20 years. I consider it to be a compliment and correct them only if it is appropriate to the situation.

Well, I get taken as male a lot, but people have always thought I looked older than I was.  Most likely, it came from how I carried myself (I act a lot more mature than most my age...in certain company, that is. xD )), and how properly I was able to speak.  I was 15 and being asked at Olive Garden if I'd like wine.  I was 16 and people assumed I was over 18 when they met me.  Now, on the cusp of adulthood, I go to buy movie tickets, and don't get carded. (This happened the other day! I didn't know whether to be glad or mad that they thought I was old enough not to be carded for an R rated movie!)  So, I guess I don't have that issue.  Judging by the posts on this thread, I might be a little lucky to not be thought of as half my age.

I've always looked younger than I am--it used to bug me but now I take it as a compliment I do correct folks and they're usually quite surprised (I'm 44)

I don't correct them unless they ask, or they make multiple comments about my age/looks and I know I have to be around them a lot more or see them again. I went on vacation with a daughter of my mom's friend and she had assumed I was a young or mid-teen (I'm 19). Our vacation house was problem-ridden, and every worker who came by asked for my parents. I told the girl (woman, whatever) because she asked how old I was, but I didn't bother with the workers I might see once or twice for a few minutes.

It does get awkward sometimes, though. My hairdresser commented on how I must like getting the day off, and when I said that I'd graduated that summer, she assumed that I graduated young and must have scholarships and such. Neither are true, lmao. I didn't wore the her because I was happy to be passing and I look much to young to be a man.

I know I'll appreciate my baby face and slimness when I'm older, but like, I'm finally an adult who everyone sees as a middle schooler. Not overly fun right now.

I seem to be the odd one out when it comes to being aged much younger than I actually am. I've always been aged older. When I was 14, people would ask what I was studying in college. Sometime around 19 or 20, a real estate agent told me I sounded much older on the phone. She was probably telling the truth, I copy my uncle when on the phone and he does the very professional tone thing on the phone. I am now in my twenties and told a friend I'm actually about ten years younger than she thought I was. "No you're not." "Uh. Yes, I am."

It's not like I have wrinkles or anything, so I think it's mostly that I dress and talk professionally. I like being considered about ten years older than I am, it usually means being treated like I know a thing or two instead of being talked down to.

I am 21 now, started transitioning at 19, when I passed for 15-16, I still get people assuming I'm a teenager. I was at an ER for a broken toe and the doc thought I was under eighteen and tried to have my mom sign my form. It can be annoying but I don't bother correcting since I've come to accept it because I know as long as I have my acne I'm gonna look younger and its not worth the effort to be constantly correcting people.I am at about 2 years on T and am hoping the acne will go away by my year 3 mark.

Recently, a colleague of around my own age--but someone new to the profession--was talking to me as if I were much younger than he and about as inexperienced. I think he was working on his second career. Well, so am I! But I let him say his piece, and I didn't bother correcting him (that is, I didn't say I'd been doing this job for a long time). He did seem confused later when he found out some stuff that didn't jibe with the age he must have had in mind. At the time, I thought the conversation was proceeding in an odd direction. Looking back, I now see that he must have been doing some mental arithmetic on the fly but was coming up short.

I keep thinking that the gray at my temples is a dead giveaway that I'm not a young thing anymore, but lots of people are prematurely gray. I still have no wrinkles, and my beard has only a few gray hairs. So he might have thought I was in my early thirties or something.

Still, that's a far cry from seventeen.

Only if they specifically say something age-related.  Sometimes you can just tell people think you're mad young.  In those cases I just let it be.  If someone says something like "this was probably before your time..." and then mentions something that I'm quite familiar with I'll correct them and inform them of my age. 

Its never been a huge issue.  Usually its one of amusement. 

I'm 27 but can pass easily for late teenager but thats something i've always really liked. In fact i was worried about starting T cos i had heard that it "ages" you! I can see how it could be frustrating for people though if they really dont like being percieved as younger than they are, depends on the situation as well

This actually happened to me today at work, a girl asked me how old I was and when I told her I was 26 she was shocked haha she still didn't believe me after I told her my birthday and everything. She said she thought I was 19 or 20...I don't really let the age thing bug me so much. It's mainly whether they recognize me as male or not is the thing that will bug me.

Me and another trans guy were leaving base this evening.  He got stopped and asked how old he was (they didn't believe he was old enough to be there), and I thought I'd miraculously appeared older than he was even though I'm two years younger.  Then our friend asked how old he thought I was, and he said 13.  Wow, yeah only five years off there mate!  As we came back in he was still questioning me, he really didn't believe it, but I'll never see him again.  On the other hand I nearly didn't get IDed for baccy this morning, but as I already had it out she asked to see it anyway.

I am 27 and get carded for everything. Two weeks ago I was carded while buying a rated R movie. I got stopped at the casino twice in a row, one guy interrogated me for almost 5 minutes, I was with my brother and his girlfriend, both 3 years younger than me. If I go to the liquor store with my brother he usually doesn't get carded, I always do. I have been working with the same people for 9 years and some of them still think I'm younger than 20. The only time I correct people is when I'm in a situation where I have to. I usually just take it as a compliment.