In Original D&D Book III:
Player/Characters must pay Gold Pieces equal to 1% of their experience points for support and upkeep, until such time as they build a stronghold. If the stronghold is in a wilderness area, all support and upkeep costs then cease, but if it is in a village or town not controlled by the player/character, then support and upkeep payments must continue.THE UNDERWORLD & WILDERNESS ADVENTURES, page 24
I was pointed in this direction while reading an old article in White Dwarf magazine which included:
The easiest way to keep track of game time is to count one real week equal to one game week, regardless of what adventures go on during the week. (I’ve tried different methods, but weeks long wilderness adventures have always thrown them out of kilter.) If a character goes on no adventure during the week he can spend the time learning a language (assuming someone/thing is available to teach it) or attending to his magic. This also makes it easy to keep an account of living expenses as per Volume 3 – I interpret it as 5% of experience points worth of gold every five weeks.D&D Campaigns Part III: Rules Recommendations (by Lewis Pulsipher), White Dwarf #5
Upkeep and living expenses aren’t directly addressed in B/X D&D, and I don’t recall really seeing anything about it back in the day. I am pretty sure that it was Traveller’s long-term subsistence guidelines that got me thinking about how to implement it in D&D.
It wasn’t until a few years ago that I really started charging “upkeep” costs, and at some point I settled on 1 gold piece per experience level per day of game time between session. I’ve ruled that this upkeep cost includes all standard food, lodging, and basic maintenance on weapons, armor, and other gear that isn’t gamed out during a play session. Mundane daily incidental expenses are considered covered.
When charged weekly, 1% of XP is far more expensive than 1 GP/level/day. A second level fighter with 2,500 XP will pay 25 GP per week at 1% of XP, while the same character would pay 14 GP per week at 1 GP/level/day. A seventh-level magic-user with 95,000 XP pays 950 GP per week at 1% of XP or only 49 GP at 1 GP/level/day. That magic-user will spend 3,800 GP per month, which seems really excessive to me.
Maybe the 1% of XP cost was intended to be charged monthly? Then our 2nd-level fighter pays 6 GP per week instead of 25 and the 7th-level magic-user pays 237 GP per week instead of 950. A lot more reasonable, but it still far outstrips my 1 GP/level/day as the XP increases.