Here is a simple and I think helpful budgeting rule-of-thumb that a CMO at a $5b software vendor shared with me yesterday:
1) 75% of your budget should be in support of revenue-generation for your current operating year.
2) 15% of your budget should be placed towards efforts that have a 2-3 year time horizon.
3) 10% of your budget should be for activity or initiatives with no time horizon,
-- Rich Vancil