"There is no such thing as a free lunch" probably could be rephrased to read "there is no such thing as a free horse!"
Before buying a horse or accepting one for free, careful consideration should be given to the costs of horse ownership:
Boarding: It is common for people to board their horses rather than to keep them at home since many horse owners are urban dwellers. However, even if you have the space, a busy work schedule may dictate that boarding is a necessity. Boarding costs vary depending on the type of facility – a large commercial stable versus a small rural barn, for example. Price can also depend on whether the horse is stalled daily and given daily access to pasture or paddocks, or kept in a field with a "run in/run out "type of housing. Presence of and access to a riding arena can also increase the cost.
Your own barn: Lucky you! You can look after your horse yourself, but there are other costs attached to this kind of ownership. You will need to procure feed and bedding (straw or shavings are common). There is also the time commitment to twice daily ‘chore time,’ which will involve feeding, watering, turn-out and exercise, as well as cleaning out the stall. As the pile outside the barn grows higher with discarded bedding and manure from the stall, you will need to consider how to manage it or have it removed periodically. You will also need to erect and maintain a fenced area for turn-out – paddock and pasture if space permits. Electric fencing, and post and rail or board are popular types of fences. You will need a reliable, good quality water source that is available winter, spring, fall and summer!
Feed costs: If your horse is boarded, the pasture or hay that your horse consumes is generally included in your monthly board fee. However, there could be extra costs for any other feedstuffs and supplements that your horse may require (see section on nutrition).
Veterinary costs: Even if your horse appears to be healthy, regular veterinary care is advisable to help maintain his good health status. Vaccinations and dental care are just two examples of services that your veterinarian will recommend to help keep your horse in optimal health.
Farrier costs: Regular hoof trimming every 6-8 weeks (+/-) will help keep his hooves in good condition and prevent lameness. Shoes may be recommended for some horses depending on the type of surface they will be working on, the amount of work they will be doing, and the horse’s hoof condition and conformation.