Jonathan Tam is a paralegal practicing legal services as a sole proprietor. He meets all of his clients in his office in the basement of his home. He lives in a house of 2,700 square feet, 900 square feet is considered to be attributable to his home office. Jonathan incurred the following costs during the current year:

Business liability insurance $ 600

House insurance 1,860

House Utilities 3,600

House repairs and maintenance 4,000

Mortgage interest 8,700

Property tax 3,600

Office supplies 1,760

What is the maximum expense that can be claimed with respect to the amounts listed above?

[Itemise all eligible items and show detailed calculations to get proper credit]