In this guide · 8 sections
- 01Why separate shop and website systems cause overselling
- 02Unified POS options for Singapore retail shops
- 03How to set up one inventory for shop and website
- 04Click and collect, and returns across channels
- 05GST-correct receipts at the counter and online
- 06End-of-day reconciliation into Xero
- 07Do it yourself or get help?
- 08Frequently asked questions
Short answer
Use a POS and online store that share one product catalogue and one inventory count per location, like Shopify with Shopify POS. Sales at the counter and online then reduce the same stock. Add click and collect, and send each day's sales to Xero through an integration rather than by hand.
Why separate shop and website systems cause overselling
Many shops start with a standalone POS at the counter and a separate online store added later. Each keeps its own product list and its own stock numbers, and someone updates one from the other by hand or with a nightly export.
- Overselling: the last unit sells in the shop at 3pm; the website keeps selling it until someone updates the count.
- Double data entry: every new product, price change and promotion is set up twice.
- Mismatched prices: a sale price goes live online but not at the counter, or the reverse.
- No single customer view: a customer who buys in-store and online looks like two different people.
A unified system fixes these by design: one product record, one price, and stock tracked per location (your shop, your storeroom, a warehouse) that every channel reads from.
Unified POS options for Singapore retail shops
Several POS systems sold in Singapore offer online stores or integrations. The question is whether the shop and web store truly share one catalogue and stock, or sync two copies on a schedule. Our POS systems comparison for Singapore covers Qashier, StoreHub and Shopify POS in detail.
Shopify + Shopify POS
One systemPlan from S$39/mo; POS Pro S$129/location/mo
- One catalogue and stock count for shop and web
- Click and collect from store stock
- Returns at any location on POS Pro
- Large app ecosystem, including Xero
Best for: Shops where online sales matter as much as the counter.
Local POS with web store add-on
Vendor quote
- Strong for F&B and local payment methods
- Web store may be simpler
- Check whether stock syncs live or on a schedule
Best for: Shops that are mainly counter sales with a small online range.
Separate POS and website linked by an app
Two subscriptions plus connector
- Keeps your existing POS
- Sync delays and mapping errors are common
- More things to break
Best for: A stopgap while you plan a move.
Shopify prices are from Shopify's POS pricing page and Singapore plan pricing, approximate as of October 2026. Shopify lists inventory management, returns and exchanges at any location, and omnichannel selling among the POS Pro features; the basic POS included with every plan handles returns at the original purchase location only.
How to set up one inventory for shop and website
Whatever system you choose, the setup order is the same. Getting the product data right first saves weeks of fixing later.
Clean the product list before importing
One record per product, consistent names, variants (size, colour) as options, and a unique SKU and barcode on every variant.
Create a location for each stock point
Shop, storeroom, warehouse. Stock is counted per location, and you choose which locations fulfil online orders.
Do a full stock count on go-live day
Count every location and enter the real numbers. Starting from guessed figures is the main reason sync "doesn't work".
Turn on inventory tracking and stop overselling
Track quantity on every variant, and switch off "continue selling when out of stock" except for made-to-order items.
Scan barcodes at the counter
Typing product names at the till picks the wrong variant. Print barcodes for items that don't have one.
Set a weekly cycle count
Count a few product groups each week and correct differences. Small, regular counts catch theft and mistakes early.
Click and collect, and returns across channels
Once stock is shared, you can offer customers more ways to buy without extra admin.
- Click and collect: Shopify's local pickup settings let customers choose pickup at one of your locations at checkout. Stock comes off that location, so only what is on the shelf can be reserved.
- Pickup notifications: send a "ready for collection" email or SMS only after staff have physically picked and bagged the order.
- Returns of online orders in the shop: decide your policy first (refund, exchange, store credit). With POS Pro, Shopify allows returns and exchanges at any location; on basic POS, returns are at the original location.
- Refund method: online card payments are usually refunded to the card; agree what staff do for PayNow orders so refunds are recorded properly.
GST-correct receipts at the counter and online
If you are GST-registered, receipts from both channels must carry the right information, and the POS and web store must use the same tax settings.
IRAS says on its invoicing page that you may issue a simplified tax invoice when the total payable including GST does not exceed S$1,000. It needs your name, address and GST registration number, the date, an invoice number, a description of the goods, and the total including GST with a statement that the price includes GST.
Receipt check for GST-registered shops
End-of-day reconciliation into Xero
Each day you have cash in the till, card terminal settlements, PayNow receipts and online payouts arriving on different days. Recording each bank deposit as "sales" will never match.
- Send a daily sales summary from the POS and store to Xero, split by payment method, using an integration such as the Shopify app for Xero.
- Post card and online payments to a clearing account; when the payout arrives, match it against the clearing account and record fees separately.
- Count the cash drawer at close, record differences, and bank cash on a fixed schedule.
- Check refunds and exchanges appear in the same day's summary, not as unexplained bank movements.
Our guide to connecting Shopify, Stripe and Xero explains the clearing account method step by step.
Do it yourself or get help?
A shop with under a hundred products can set up Shopify and Shopify POS itself, especially if the products are already in a spreadsheet. Budget a full day for the first stock count. Our guide to what a Shopify store costs in Singapore helps you price it.
Get help when you have many variants, more than one location, existing data in an old POS, or need the accounting side right from day one. Our Shopify Store package (S$1,890) sets up the store and POS from one catalogue; Online Store Pro (S$3,490) suits larger catalogues and multiple locations; Xero / QuickBooks Integration (S$390) handles the daily reconciliation.
Frequently asked questions
Yes. The most reliable way is a POS and online store that share one product catalogue and one inventory count per location, such as Shopify with Shopify POS. Separate systems linked by a connector app can work but often sync on a delay, which leads to overselling during busy periods.
Basic in-person selling is included with every Shopify plan, which starts at S$39 a month paid monthly. POS Pro, which adds returns at any location, inventory management and staff permissions, was listed at S$129 per location per month as of October 2026. Payment fees and hardware are extra.
Turn on local pickup for your shop location in the store's shipping settings. Customers then choose pickup at checkout and stock is taken from that location. Hold picked items on a separate shelf and only mark orders fulfilled when the customer collects, so walk-in buyers cannot take reserved stock.
You can allow it, and many customers expect it. Decide whether you refund, exchange or give store credit. On Shopify, POS Pro supports returns and exchanges at any location, while the basic POS handles returns only at the original purchase location. Record every return in the system, not just the till.
IRAS allows a simplified tax invoice when the total payable including GST does not exceed S$1,000. It shows your name, address and GST registration number, the date, an invoice number, a description and the GST-inclusive total. Provide a full tax invoice for larger sales and when business customers ask.