Separate one-time and recurring costs
List the acquisition fee, initial veterinary care, transport and equipment separately from food, preventive care, training and other ongoing costs. Ask local providers for current quotes. A number copied from another country or year can be a poor planning tool.
Include the awkward expenses
Consider boarding, paid help during illness, replacing outgrown equipment and vehicle arrangements. Discuss how the household would meet an unexpected veterinary bill. Insurance and savings involve different constraints, so compare the actual terms and your ability to pay at the time of care.
Write the assumptions down
For each estimate, record the provider, date and what is included. Revisit the worksheet as the dog grows or your circumstances change. If the plan relies on every month being inexpensive, adjust it before committing to a dog.