I am buying a house with 100amp service and the home inspecter said I would need at least 150 amp panel to service the hot tub that comes with the home. However, the hot tub is hooked up to the 100amp service panel and the hot tub works fine. Am I really running into any issues here if I do nothing? The seller will not install 150 amp service because he feels he doesn't have to. If I need to do something, I want to know how much I should ask at closing to fix. Please advise. Thanks

If it is working fine then what is there to "fix". An upgrade would be just that, an upgrade.

Did anyone do a load calculation?

While a 200A service will definitely do you good in the long run, a 100A service is very likely not a "defect" at this time.

Thanks Stan.

If you need more spaces for breakers so that you can add new loads to your 100 amp panel, the cost to in stall a new 200 amp panel with breakers, mast, meter base,will cost $1800 to $2200 Taxed and Permit plus new connection fee

If you need more spaces for breakers so that you can add new loads to your 100 amp panel, the cost to in stall a new 200 amp panel with breakers, mast, meter base,will cost $1800 to $2200 Taxed and Permit plus new connection feeOr around $3500 if the OP is in California. ;)

Also, you might want to check the dates of the posts you are replying to. :)

Some municipalities require certain upgrades when a property changes hands. A 200 amp upgrade is never a bad idea. You have to look at how much electricity is actually being used when the hot tub is running. Do the lights dim if the refrigerator switch on. Do the get brighter when the hot tub is turned off. Typically hot tubs are on a separate 30 amp circuit because of the pump and heaters.