The payback calculation
If your destination leaves you $600 extra per month and the net unreimbursed move costs $6,000, your planning break-even is 10 months. The formula is one-time cost divided by positive monthly improvement. It is an intentionally simple, transparent model; salary changes and price inflation can alter the future.
Use net moving cost, not just a headline mover quote
Add moving services, temporary living costs, duplicated rent and unavoidable setup charges. Then subtract reimbursements you can reasonably count on. Treat refundable deposits as a temporary liquidity need rather than a permanent expense if you expect them returned. If reimbursement will be delayed, consider a separate cash-reserve plan.
What if the offer costs you money every month?
If recurring costs outpace the after-tax pay increase, there is no positive break-even date using stable monthly inputs. This does not prove the relocation is a bad life decision. It tells you that the financial return requires a different assumption, new compensation, lower ongoing costs or a nonfinancial reason.
A 12-, 24- and 36-month comparison
The short-term outcome can be negative even when the long-term one turns positive. Compare at least three horizons. If you expect to move again or change jobs quickly, do not use a five-year payback as proof that the offer is attractive.
Uncertainty matters more than extra decimal places
Round planning inputs to realistic amounts, keep the source of each estimate and explore an adverse scenario. A $300 shift in rent or a change in benefits can matter much more than a supposedly precise income-tax percentage. Run the interactive calculator with your own ranges.