1,073. Writing on Chol Hamoed

Hilchos Shvisas Yom Tov 7:13

It is not permitted to write professionally on chol hamoed - not even Torah scrolls, tefillin and mezuzos. One may not check a Torah, not even one letter in the scroll that was kept in the Temple courtyard, because doing so is not a labor that is needed for yom tov. One may, however, write tefillin or mezuzot for his own use, or spin techeiles (blue wool) for his own garment. If one has nothing to eat, he may write professionally and sell the resulting product to others in order to earn a livelihood.

Hilchos Shvisas Yom Tov 7:14

It is permitted to write personal correspondence on chol hamoed. Similarly, one may make an accounting of his budget and expenses because one does not take particular care when writing such things, so they are like tasks being performed by an unskilled person.