In most jurisdictions the tax department will want you to keep documentation to support the tax you are claiming. For items your business purchased that means keeping receipts. For items your business sells, you must issue a tax invoice so the purchaser can claim a deduction.
If you interact with another business as both a supplier and customer you need to:
- Record the sales in Manager with them as a customer (and you issue a receipt).
- Record the purchases in Manager with them as supplier (and they issue a receipt to you)
- Manager will then also record the sales and purchase totals as you describe
Alternatively if your customer is supplying some components, you can invoice the customer for the goods and services your business is actually supplying which is likely to show
- Total project cost as a positive line item(s)
- Items customer lends to you for commissioning (they were never yours to use as you wish), entered as negative line item(s).
- Probably a commissioning / integration percentage for components supplied by the customer (a positive line item)
- Invoice total showing net goods & services your business contributed
- Note this approach does not require your customer to invoice you for components they supply, and correspondingly nor will these items add to both your total purchases and sales
Manager can record either business arrangement, you just need to enter purchases as purchases via the “Purchase invoice” tab and sales as sales via the “Sales invoice” tab. The totals and invoices are then efficiently handled by Manger.
A separate issue is the fluency with which Manger handles accounts between related entities such as
- A business which is both a customer and supplier
- A business which has several sub divisions
I can see scope for Manager to better handle these aggregate relationships (although I personally have no need for the capability).