what do tax preparers do for the rest of the year when people don't file taxes?

Late taxes, quarterly taxes, early taxes... There's always taxes, but yes a lot of the h&r block types only do tax prep for a few months and another job the rest of the year

Corporate taxes - at least in Canada, you can have a year end any day of the year.

And yes, some older tax preparers don’t work in summer/fall.

Often, at firms, staff will be brought in from other groups during tax busy season to prepare returns. The rest of the year they are on audits or other work.

The reviewers and tax professionals do not switch groups. They do advisory, planning, other compliance, business development, training and binge drinking the rest of the year.

other accountancy or financial planning work

Some tax preparers are semi-retired folks who work just part of the year by choice.

Technically taxes are due quarterly in the US, so they have plenty to do if they have business or self employed customers. My dad was a tax preparer and would file tons of extensions in April and finish them up until August. Then start on the next year.

Plot.

Lobby for making taxes more complicated /s

In the Midwest, some farm.