Make the build vs buy decision with real numbers. Compare the total cost of outsourcing any business function against in-house hiring, including hidden employment costs and management overhead.
The outsourcing decision is often made on intuition or cost at face value. The rigorous comparison accounts for: full employment cost (not just salary), management overhead of the outsourcing relationship, quality differential (outsourced work often requires more management to achieve equivalent output), and recruitment and onboarding cost amortised over expected tenure.
Volume is variable (avoid paying for idle capacity), specialist skills needed intermittently, function is non-core, quality requirement can be met externally, supplier market is competitive and delivers good value, management overhead is manageable relative to the function's complexity.
Function is a core competency or competitive differentiator, institutional knowledge is critical, quality requirements are very high and hard to specify in a contract, regulatory or data sensitivity requirements limit external sharing, the total cost difference is small but the control benefit is large.
Outsourcing is typically cheaper than hiring when: (1) The outsourcing cost including management overhead is below the total employment cost (salary + NI + pension + overhead + recruitment amortised); (2) Demand is variable and you are not paying for idle time; (3) The function does not require institutional knowledge that takes months to develop. The comparison must use total employment cost, not just salary. Many businesses compare outsourcing monthly cost against salary alone and reach the wrong conclusion.