For retirement budgeting purposes, I need to identify my 'mandatory' expenditure over the past few years, and for future transactions. The obvious way to do that would seem to be with a 'mandatory' tag. But as far as I can tell, tags apply to individual transactions - which is fine - but certain *categories* will always be mandatory (local taxation, for example) and remembering to apply the tag every time may become irritating and prone to error. Is it possible to tag a particular *category* as 'mandatory' expenditure rather than all its individual transactions? There's no option for it that I can see.

If there are alternative (better!) approaches to this, then please share :-)

Thanks