[Avodah] Why should one have to make Hataras Nedarim every year?

[Mandel, Seth via Avodah]

From: Professor L. Levine <llevine at stevens.edu>
Sent: September 20, 2016 at 1:24:51 PM
> In light of this, why should one have to make Hataras nedarim every
> year? It seems to me that saying it once should suffice forever.

Hattarat n'darim before RhS is a late minhag and had nothing to do
with Hattarat n'darim from the Torah. In fact, you need to do Hattarat
n'darim for any neder you need to be mattir during the year according
to the poskim. It is still a minhag and not an obligation, but almost
everyone does it because it is printed in the siddur.