Guides & video tutorials: GST returns, e-invoicing, WhatsApp setup and 399Apps walkthroughs

• Migration

  Migrate from Tally to 399Apps

  To move from Tally to 399Apps, export your masters (ledgers, parties and stock items), opening balances and outstanding invoices from TallyPrime to Excel/CSV, clean the sheets, then import them into Nidhi Books and reconcile against your Tally trial balance. Pick a clean cut-over date — usually a month or quarter start — and run both systems in parallel for one cycle before going fully live. Guided onboarding support is available for larger datasets.

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• Migration

  Migrate from Marg ERP to 399Apps

  To move from Marg ERP to 399Apps, export your masters (parties, items and stock), opening balances and outstanding invoices from Marg to Excel/CSV, clean the sheets, then import them into Nidhi Books and reconcile against your Marg trial balance and stock report. Pick a clean cut-over date — usually a month or quarter start — and run both systems in parallel for one cycle before going fully live. Guided onboarding support is available for larger datasets.

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• Migration

  Migrate from Vyapar to 399Apps

  To move from Vyapar to 399Apps, export your parties (customers and suppliers), item/stock list and opening balances from Vyapar to Excel/CSV, clean the sheets, then import them into Nidhi Books and reconcile against your Vyapar reports. Pick a clean cut-over date — usually a month or quarter start — and run both apps in parallel for one cycle before going fully live. Guided onboarding support is available for larger datasets.

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• Migration

  Migrate from myBillBook to 399Apps

  To move from myBillBook to 399Apps, export your parties, item/stock list and outstanding invoices from myBillBook to Excel, then import them into Nidhi Books and set opening balances on a clean cut-over date. Add your whole team — 399Apps charges no per-user fee. Run both for one GST period before retiring myBillBook.

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• GST returns

  How to file GSTR-1

  GSTR-1 is the monthly or quarterly GST return where you report all outward supplies (sales). To file it, log in to the GST portal, open the Returns Dashboard, select the period, add your B2B, B2C, export and credit/debit-note details (or upload them in bulk), generate the summary, then submit with a DSC or EVC.

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• GST returns

  How to file GSTR-3B

  GSTR-3B is the monthly self-assessed summary return where you declare total outward supplies, the input tax credit (ITC) you claim and the net GST payable. To file it, log in to the GST portal, open the GSTR-3B tile for the period, verify the auto-filled values, offset your liability with ITC and cash, then submit with a DSC or EVC.

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• GST compliance

  What is e-invoicing under GST

  E-invoicing under GST is the system where B2B invoices are uploaded to a government Invoice Registration Portal (IRP), which validates them and returns a unique Invoice Reference Number (IRN) and a digitally signed QR code. It is mandatory for businesses whose annual aggregate turnover exceeds ₹5 crore in any year since 2017-18.

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• GST compliance

  GST late fees & interest

  If you file a GST return after the due date, you pay a late fee of ₹50 per day (₹20 per day for nil returns), split equally between CGST and SGST, plus 18% annual interest on any tax paid late. Late fees are capped based on your turnover and the type of return, so they do not grow without limit.

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• GST billing

  GST invoice format

  A GST tax invoice must show the supplier’s and recipient’s name, address and GSTIN, a unique consecutive invoice number (up to 16 characters) and date, the HSN/SAC code, item description, quantity, taxable value, the GST rate and amount split into CGST/SGST or IGST, the place of supply, and the supplier’s signature or digital signature.

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• Video tutorial

  How to create a GST invoice on mobile

  Open the Sales menu in Nidhi Books on your phone browser, create a quotation with your line items, HSN, discount and place of supply, then convert the accepted quotation into an invoice in one tap. Issue the invoice to generate its GST number, record the payment (including TDS withheld and a payment proof), and any balance stays as customer credit.

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• WhatsApp

  Get your WhatsApp Business API credentials

  Meta gives you four credentials. Your WhatsApp Business Account ID (WABA ID) and Phone Number ID are on the WhatsApp → API Setup page of your Meta app. Your permanent access token comes from Business Settings → System Users. Your App Secret is on App Settings → Basic. Paste all four into 399Apps, add the webhook URL back into Meta, and you are sending.

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• WhatsApp

  WhatsApp sending methods: which one do you need?

  399Apps has three ways to send on WhatsApp. Quick send (wa.me) works instantly with no setup — you tap send and your own WhatsApp opens with the message ready. The Meta Cloud API sends automatically from your own business number with no human present. A QR gateway pairs by scanning a code and needs no Meta account. Most shops need only quick send; switch to the Cloud API when messages have to go out on their own.

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• WhatsApp

  WhatsApp Business API cost in India, per message

  In India, Meta charges ₹0.8631 per marketing message and ₹0.1150 per utility or authentication message, plus 18% GST, billed in rupees. Customer messages to you are free. A shop sending 300 bills and one 1,000-customer offer a month pays Meta about ₹1,059. A BSP adds a monthly fee and usually a markup; 399Apps adds nothing.

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• Business formats

  Quotation format

  A quotation should show your business name and GSTIN, a quotation number and date, a validity date, the customer’s details, each item with description, HSN/SAC, quantity, rate, discount and GST, the total in figures and words, and your payment, delivery and warranty terms, signed by the person authorised to quote. Download the free template below.

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• Business formats

  Proforma invoice format

  A proforma invoice is a preliminary bill a seller sends before supplying goods or services, to confirm the order and its price and to ask for an advance. It is not a tax invoice under GST: it creates no GST liability, is not reported in GSTR-1, and the buyer cannot claim input tax credit on it. The tax invoice follows on supply.

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• Business formats

  Delivery challan format

  A delivery challan is the document that goes with goods moved without a tax invoice — for job work, supply on approval, goods sent in batches or movement that is not a supply. Under Rule 55 it must show the challan number and date, consignor and consignee details with GSTIN, HSN, description, quantity, taxable value, tax where applicable, place of supply and a signature.

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• Business formats

  Bill book format

  A GST bill book is a pre-numbered book of tax invoice leaves, printed in three copies for goods and two for services. Every leaf must carry your name, address and GSTIN, a consecutive bill number unique for the financial year, the date, buyer details, HSN/SAC, quantity, taxable value, GST rate and amount, place of supply and a signature.

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• Business formats

  Purchase order format

  A purchase order (PO) is the document a buyer sends a supplier to order goods or services at an agreed price. A complete PO shows a PO number and date, buyer and supplier names, addresses and GSTINs, the delivery address and date, item description, HSN or SAC, quantity, rate, GST, the total, payment terms and an authorised signature.

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Looking for quick answers instead? See our GST & software answers or GST glossary.