The gemara has 2 versions of Rava whether when one gives against the receiver's will, but in his presence, whether that qualifies as having been given (when not in the receiver's presence all agree that it does not qualify as giving). Tosafos qualifies the opinion that considers giving against the receiver's will not to be considered giving - this only applies when it is detrimental to the receiver to get the money because he will have to give something in return, but if the receiver will not loose anything then it would be considered giving provided that the money is owed. But if the money is a gift, all would agree that one cannot force someone else to receive a gift against his will. In short, all agree that a gift cannot be given against the receiver's will. All agree that when the money is owed and the receiver has nothing to loose by receiving it, it is considered giving even against his will. They argue only in a situation where the money is owed, but the receiver has something to loose.
The Beis Yosef has a discussion what the definition of "giving against his will" is. Does it mean that you can force him to physically receive the money (by forcing the money into his hand) or is it sufficient to simply give it without him receiving at all? The Taz (E.H. 143:9) proves that the opinion who considers giving against his will to be considered giving, will hold that you can simply throw it down in front of him, and there is no requirement that he receive it at all. Tosafos asks that according to the opinion that giving against his will does not qualify as giving, why should the purchaser of a house in a walled city have to hide to avoid the seller redeeming his house; he should simply refuse to receive the money? From the fact that Tosafos doesn't ask this question even in the opinion that giving against his will qualifies as giving, implies that according to that opinion the refusal to receive the money would not help because he can just throw it down in front of him, therefore the buyer had to hide.
The gemara earlier had a discussion where he make a condition with her that it would only be a gett if she would give him a specific garment. We pasken like the Rabbonon that money cannot be given instead. The Rosh holds that this is only if the husband insists on the garment, but if he agrees to accept money all agree that the condition can be met by paying money. The Beis Shmuel (143:10) points out that based on this, the entire machlokes Rashbag and Chachamim would only be when he demands the garment and does not agree to accept money in it's place.The Rabbonon would say that since a garment was stipulated, he cannot be forced to accept money in lieu of the garment. The B"S points out that this doesn't relate to the argument of giving against his will, because even if normally he can be forced to accept the money against his will, however, when the garment was specifically stipulated he can insist on receiving the garment itself. However, the B"S points out that we should be able to point out from here that normally giving against his will qualifies as giving, since the only reason he cannot be forced to accept the money is because the garment was stipulated, but otherwise he can be forced to accept the money?