How to make money as Tomb Kings

Tomb Kings's fastest-paying building in Total War: Warhammer III is the Charnel Plaza (Income, level 1): 250 gold for +100 gold a turn, its cost back in 2.5 turns once built. The most gold from one building slot is the Undead Fleetport at +300 a turn (7,000 gold to build the chain that far, back in 23.3 turns). 8 Tomb Kings building levels make flat income, patch 9.0.4.

Fastest payback

Turns of income to earn the building's cost back (each chain's fastest level).

1Charnel PlazaIncome 1 · 250 gold → +100 a turn · Any settlement2.5turns
2Gold MineGold Mining 1 · 1,000 gold → +150 a turn · Region with the resource6.7turns
3Parched OasisPastures 1 · 1,000 gold → +100 a turn · Region with the resource10turns
4Undead FleetportPort 3 · 4,000 gold → +300 a turn · Port settlement13.3turns

Most gold per building slot

Income of each chain's top level; the line shows that level's own cost.

1Undead FleetportPort 3 · 4,000 gold → +300 a turn · Port settlement+300a turn
2Avenue of MonumentsIncome 3 · 1,000 gold → +200 a turn · Any settlement+200a turn
3Gold MineGold Mining 1 · 1,000 gold → +150 a turn · Region with the resource+150a turn
4Parched OasisPastures 1 · 1,000 gold → +100 a turn · Region with the resource+100a turn

COMPUTEDIncome = the level's flat gold per turn (the game's “Income generated” effects on the building itself, table building_effects_junction) minus its upkeep (building_levels.upkeep_cost). Payback = cost (create_cost) ÷ income. Upgrade payback = the level's cost ÷ the income it adds over the level below. “Gold back by turn” = build turns (create_time) + payback, counted from the order. Chain total = every level's cost up to this one, and its payback = that total ÷ income. Patch 9.0.4.

ASSUMPTIONS

Base values: technologies, lord skills, commandments, campaign difficulty and faction effects that change income or building costs are not counted.
Percentage boosts (“+4% income from all buildings in the province”, “+20% (local region)”) are not in the payback: they depend on the buildings they boost. They are listed below with the income those buildings need to make.
Conditional income (“When Control is 75 or more”, “When enemy Lord is present”…) is not counted; listed below in the game's words.
Resource buildings need a region with that resource; ports need a port settlement. A slot can hold one building, so late in a campaign gold per slot matters more than payback.

Every Tomb Kings building that makes gold (8)

#
1	Charnel Plaza	Income	1	250	1	100	2.50	—	3.50	Any settlement
2	Funerary District	Income	2	500	2	150	3.30	10	5.30	Any settlement
3	Avenue of Monuments	Income	3	1,000	3	200	5	20	8	Any settlement
4	Gold Mine	Gold Mining	1	1,000	2	150	6.70	—	8.70	Region with the resource
5	Parched Oasis	Pastures	1	1,000	2	100	10	—	12	Region with the resource
6	Bone Wharf	Port	1	1,000	3	75	13.30	—	16.30	Port settlement
7	Grave Port	Port	2	2,000	5	150	13.30	26.70	18.30	Port settlement
8	Undead Fleetport	Port	3	4,000	7	300	13.30	26.70	20.30	Port settlement

Main building levels

Settlement upgrades make gold too, but they also cost growth (population surplus) and open building slots, so payback alone undersells them. Province capitals and minor settlements are separate chains.

#
1	Crypts	Province Capital	1	750	—	50	—
2	Crypts	Minor Settlement	1	750	—	50	—
3	Mastaba	Province Capital	2	1,500	1	100	30
4	Mastaba	Minor Settlement	2	1,500	1	100	30
5	Mausoleum	Province Capital	3	3,000	2	150	60
6	Mausoleum	Minor Settlement	3	3,000	2	150	60
7	Tomb City	Province Capital	4	6,000	4	200	120
8	Necropolis	Province Capital	5	12,000	5	250	240

Every level's full effects: Tomb Kings buildings.