The cost of bookkeeping services for interior designers can vary based on factors like the size of the business, the volume of transactions, and the complexity of financials. On average, monthly bookkeeping fees for small to medium-sized interior design businesses range from $200 to $600. Larger firms might pay between $600 and $1,500 per month. Hiring a professional bookkeeper helps designers maintain accurate records, monitor cash flow, and save time for their creative pursuits.