On Customers, add each buyer once with their name, phone and KRA PIN, and their total invoiced, paid and balance fill in on their own. On Line Items, itemise each invoice with a description, quantity and unit price. On Invoices, add the header, pick the customer and enter the amount paid: the subtotal pulls from the line items, VAT is added at 16%, and the total and balance are worked out.
The Summary shows net sales, VAT charged, gross sales, collected and outstanding across the whole book, with a Paid, Partial or Unpaid status on every invoice. Yellow cells are your only inputs. The premium version adds a sales dashboard, reports by month and customer, and a printable A4 tax invoice for any invoice number you pick. Opens in Excel, WPS or Google Sheets.