# 3. Costs and Payment

Understand purchase cost, average cost, payments, and vendor balances.

# How purchase cost works for itemized inventory

**In this guide:** Understand how receiving itemized stock can change the product cost used for reporting and profit calculations.

## Enter the correct cost

On each itemized purchase line, enter the cost for one unit. RepairNest POS adds the received quantity to the location's stock and applies the cost behavior configured in **Settings > Inventory**.

## Average-cost example

If you already have 10 units at a $5 average cost and receive 10 more at $7 each, the combined average cost becomes $6 per unit:

**(10 × $5 + 10 × $7) ÷ 20 = $6**

## Why it matters

- The selling price does not automatically become the purchase cost.
- Cost affects profit, margin, inventory valuation, and related reports.
- Historical purchases retain their own line costs even when the product's current average cost changes.

## Tip

Review your Inventory cost-management setting before receiving stock if your organization uses a method other than average cost.

# How purchase cost works for serialized inventory

**In this guide:** Understand why each serialized device keeps its own exact purchase cost.

## How it works

A serialized item is purchased and sold using its exact IMEI or serial number. The cost entered for that identifier stays attached to that individual unit, so profit can be calculated from the actual device acquired and sold.

## Steps

1. Add the serialized product to the purchase.
2. Enter each unique IMEI or serial number.
3. Enter the exact cost paid for each unit.
4. Save the purchase.
5. Open Serialized Inventory and verify the identifier and cost.

## Example

Two phones may share the same product name but cost $220 and $250. When one phone is sold, RepairNest POS uses the cost stored for that exact serial—not an average of both devices.

## Important

Verify identifiers before saving. Correcting the original purchase is safer than disconnecting a purchase-linked serialized record from its history.

# How to record payment or leave a vendor balance due

**In this guide:** Record how a purchase was paid or keep the amount due on the vendor account.

## Record a paid purchase

1. Review the purchase total and select **Save Purchase**.
2. Choose the payment source, such as an external payment or the register when allowed.
3. Select the configured purchase payment method.
4. Enter a payment reference when useful.
5. Confirm the amount and select **Pay & Save**.

## Leave a balance due

1. Select the vendor before saving.
2. Choose the option that keeps the purchase open or records the allowed unpaid balance.
3. Save the purchase and verify the remaining due amount on the saved record.

## Why the vendor matters

A vendor is required when a balance remains due or the purchase is consignment, because RepairNest POS needs to know which supplier account owns the balance. A fully paid purchase may be saved without a vendor, but adding one improves supplier history and invoice lookup.

*Vendor statements, balance reconciliation, and payables will be covered in a separate Vendor Accounts guide.*