Business owners, beware.

The Internal Revenue Service doesn’t consider your dog to be a “security device” or your parakeet to be “aerial surveillance.”

California tax expert Donald Fletcher might dispute that, but you might not want to trust his judgment.

Fletcher is serving a 71-month prison stretch for teaching tax-time alchemy that tried to turn personal pet expenses into business writeoffs.

According to court records, Fletcher told prospective clients he was privy to “secret” tax-saving tactics not taught at business schools such as Stanford and Harvard.

For example, if a client couldn’t put his finger on an expense, Fletcher was known to flip open a phone book and ask the client to point at a number at random.

Once, one of Fletcher’s preparers inflated a $3,277 farm expense to $54,893.

The odd thing is, Fletcher’s preparers apparently weren’t proud of their work.

Fletcher’s team urged clients to tell the IRS they had prepared their returns themselves.

On the unusual occasion they’d sign the return as required by law, they did so illegibly to thwart investigators.

Still, Fletcher’s secrets were so tempting that:

n A home-based day-care operator claimed veterinarian and pet-food bills actually were security and rodent-control expenses.

n A doctor and his wife deducted $17,384 in security expenses that actually were medical bills for an 11-year-old German shepherd that suffered from a heart condition, was immobile and had to be fed intravenously.

n That same couple also wrote off thousands of dollars in travel expenses to visit a “rental home” that happened to be in their front yard – and was occupied by the wife’s mother.