Okay just to clarify things, Wealth is a form of social influence whose output is a service or item you gain for yourself or another. You don't expend anything other than the "influence". Wealth can be substituted 1 for 1 for coin values unless your GM tells you otherwise. What that means is if you have 50 silver wealth, you have the equivalent to 50 SP that you can use monthly. Please note the use of equivalent and see below.
Very simply, you determine the value of the item or service you desire (given by the GM usually) and double it to determine the Wealth TD. So the formula looks like this:
VALUE X 2 = WEALTH TD
Make sure you convert the value to your type of wealth before rolling for the TD.
As a note, for Wealth purposes, 10 CP = 1 SP, 10 SP = 1 GC, 5 GC = 1 GS, 5 GS = 1 GB.
The wealth levels are Copper (CP), Silver (SP), Gold (GC), Noble (GS), and Royal (GB).
So with this in mind, let's say you want to use your wealth to pay to have your horse stabled for 13 days. The value is 13 SP (1 per day; hey, its close to a city so don't yell at me...). If you have 67 Copper Wealth, you would need to covert 13 SP = 130 CP and then double it to TD 260. Not good odds.
Now if you had the same Silver Wealth, the TD would be 13 double or TD 26. Much better odds.
Nobility would barely notice, having a scant TD 4 and Royalty wouldn't even have to ask for it, since negative TD means whatever it is happens automatically.
Once you use the Wealth, decrease your Wealth value for the MONTH by the VALUE (not the TD) of the item or service. If the amount would make your Wealth TD a negative value, then you have been LOANED the item or service with an expectation of repayment.
Loans are given a grace period of days equal to your original Wealth value, converted to the Wealth standard (Copper, Gold, Noble, etc.) that you used to pay them back. Loans must be redeemed at 150% item or service value.
Loans not repaid permanently lower your Wealth -d4 per day until you pay it back. Additionally, every point of Wealth lost in this manner is added together to formulate a percentage that legal or illegal action will be pursued. Which is undertaken depends on who provided the loan and ultimately the GM. Regardless, if either action is taken, it will erode the trust of contacts, connections, businesses, markets, fame in social motifs, and other like values by -d4 daily until resolved.
If your Wealth reaches zero or a negative value, you are demoted to the next lower level, and set at a value of 100.
Example: You have a 39 Silver Wealth but want a 60 Silver sword. You make the TD 120 but 39 - 60 = -21 so you have taken out a loan for it. You have 39 days to repay the loan and it will cost you 90 SP to do so. You fail to scape up the money and went out adventuring instead. You come back 9 days overdue to repay the loan and find your wealth has dropped -17. The GM secretly made a roll each day and succeeded on day 7 for illegal action to be taken to repay the loan. As they terrorized your contacts while you were out, their trust fell -3 overall as well impacted your budding reputation in the town. A couple of tough looking guys waited for you on the edge of town. Being bloody and tore up didn't seem to phase them any so they broke your legs to add to your excitement, not to mention killed your mage buddy's familiar. All in all, life is not looking good for you.