How detailed should each month's entry be?

Just the totals, this sheet is meant for the big picture; use the Monthly Budget Planner for category-level detail.

Can I fill it in ahead of time as a plan instead of a record?

Yes, it works either way, as a plan filled in ahead or a record filled in as each month closes.

The whole year on one page. See income, expenses, and savings side by side for every month, so trends and seasonal patterns are easy to spot.

Yearly Budget Overview
US Letter · PDF · Free, no signup

Fill in each month's totals as it wraps up, or plan them ahead at the start of the year.
Log Income, Expenses, and Savings separately for each month.
Look for patterns, some months always run tighter than others.
Use last year's completed sheet to plan next year's budget more accurately.

Post it somewhere visible for a full-year view of your financial trend.
Pair with the Monthly Budget Planner for the category-level detail behind each month's totals.
Keep completed sheets year to year to track long-term progress.

How detailed should each month's entry be?: Just the totals, this sheet is meant for the big picture; use the Monthly Budget Planner for category-level detail.
Can I fill it in ahead of time as a plan instead of a record?: Yes, it works either way, as a plan filled in ahead or a record filled in as each month closes.