Not sure if this topic has been discussed. It can be a good way to increase your income.
Our company is commercial and some residential, we don't do automotive. So we have an agreement with a couple of locksmiths who are strictly automotive. The way it works is a customer calls us to have a key made for their vehicle, we quote a price (based on pricesheets supplied by the automotive locksmith), we add on a percentage, 25%. If the customer wants the job we dispatch the automotive subcontractor and he knows to add 25% to his normal rate. He gives a receipt from our company. Once a month these subcontractors come in and pay us our %. Becuase we don't do automotive and they don't do what we do it works out well.
They gain by having our advertising and we gain by not having to invest in the automotive end of things.
We also subcontract with a welder to weld gates, gateboxes etc. We add his normal rate to our quotes. We don't do any mark up on his prices, it just gives us the ability to bid jobs that require welding aluminium etc. If it is a minor thing we weld it ourselves.
We subcontract all our high voltage and fire alarm work without mark up. We subcontract our glass work with no mark up.
We occasionally will subcontract a fellow locksmith that just works on safes if it is something we cannot handle. He has the ability to move safes that weigh 5000 or 6000 pounds, plus he has more expertise in really complicated openings. We are limited to 2000 pounds in weight. We use his regular prices and he gives us 20%.
The only time we don't do this is if our contract with the customer specifies that no subcontractors may be used. We have a couple of customers that so stipulate.