If i am winning on time when this happens, is it a legitimate tactic not to claim the draw?

Also, i understand that in order to claim the draw you need to press the offer draw button in live chess?

Does the above work the same way in online chess?

And finally, what about OTB? I plan to join a chess club after the holidays, so it would be useful to know. Thanks.

At the 50 move rule I believe this happens automatically - also, your opponent can claim the draw instead.

But don't do it. If the position is drawn, take a draw.

I've only had it happen once. It was a 5-minute game, and we repeated moves 3 or more times. I did not realize that i had to press the button in order for the draw to happen. I don't think my opponent did either. It would have been in his favour, as he had significantly less time than me at that point. Other than the time trouble, i don't think the position was drawn. I ended up winning on time, only later learning about the button. Hence the questions above.

You never have to claim a draw by repetition or the 50-move rule, but your opponent can always claim them himself.  Even if neither of you makes a claim, if an arbiter observes the game he could rule neither side was trying to win and declare it a draw.

Yes, click the "offer draw" button and if a legal draw has occurred, it will be automatically awarded.  If you are wrong, it still offers the draw to the opponent.  Online or turn-based games are the same.

OTB, the custom is to stop the clock, announce your intent to make a claim, summon an arbiter/tournament director, and tell him the move you intend to make and the claim, or if the conditions are fulfilled without you moving, just claim the draw.  Sometimes the opponent will just agree to the draw without calling the arbiter, in which case you simply record the result.

In casual games there may be no scoresheet kept, and no way to confirm repetition or 50 moves, but you should keep it friendly and just agree.

Thanks for clearing that up for me!

And thank you Fezzik as well. I always suspected chessplayers were more ruthless than they looked.