Invoice Number Generator.

Under GST rules, an invoice number, formally the invoice serial number, must meet a few clear conditions. It has to be a consecutive serial number that is unique within a financial year, it cannot be longer than sixteen characters, and it may contain only letters, numbers, and the special characters hyphen, dash and slash, with no spaces or other symbols. A common, compliant format is a short prefix, the financial year, and a zero-padded running number, for example INV/2026-27/0001, which is easy to read, sorts correctly, and stays within the character limit. You are free to design the scheme to suit your business, so the prefix could be your initials or a branch code, but the core requirement is that the numbers run consecutively without gaps or repeats across the year. This generator builds numbers that follow this pattern, but you remain responsible for keeping the total length within sixteen characters and using only permitted symbols, which is why it is worth checking your chosen prefix and separator against these limits before you adopt the series.

Yes, the requirement is that the invoice serial number be unique within a financial year, so it is standard and accepted practice to restart the sequence at the beginning of each financial year, which in India runs from 1 April to 31 March. Most businesses begin the new year at 0001 and let the number climb until the following 31 March, then reset. To keep numbers from different years distinct, the financial year is usually built into the invoice number itself, as in INV/2026-27/0001, so that even though the running number resets, the full invoice number never repeats across years. This makes reconciliation and record keeping cleaner, because the year is visible on the face of every invoice. If you prefer, you can run a continuous sequence that never resets, which is also acceptable as long as it stays consecutive and unique, but the year-based reset is more common and easier to audit. Whichever you choose, the golden rule is no gaps and no repeats within a year, so decide your approach at the start of the year and apply it consistently.

No, this tool does not track, store or remember your last used invoice number, and that is by design. It runs entirely in your browser with no account and no saved history, so it cannot know which numbers you have already issued. What it does is generate a sequence on demand from the start number you give it, which means you are responsible for telling it where to begin so the new numbers continue your existing series without overlapping. In practice, the safe workflow is to keep your authoritative record of issued invoices in your billing software or accounting register, check the last number you used, and then set this tool start number to one higher before generating the next batch. Because nothing is stored here, you avoid any risk of the tool being out of sync with your real records, but it does mean you must keep your own count. If you need automatic sequential numbering that never repeats, a proper invoicing system that maintains the running number for you is the right tool, with this generator best suited to planning a scheme or grabbing a batch of numbers.

Padding is the practice of writing the running number with leading zeros to a fixed width, such as 0001 instead of 1, and the right amount depends on how many invoices you expect to raise in a year. Four digits, giving numbers from 0001 to 9999, suits most small businesses comfortably, since it covers up to nearly ten thousand invoices in the year while keeping the number short. If you bill very heavily and might exceed that, choose five digits for a ceiling of 99999. The main benefit of padding is that zero-padded numbers sort and line up neatly, so 0009 and 0010 appear in the correct order in a list, whereas unpadded 9 and 10 can sort wrongly in some systems and look untidy on a printed register. Padding also makes gaps easy to spot during reconciliation. Just remember to count the padded width towards the sixteen-character limit, so a long prefix plus the financial year plus five digits should still fit. For most users, four digits is the sensible default this tool starts with.

Yes, the prefix is fully customisable, and many businesses use it to make their invoice numbers more meaningful. You can set it to a generic INV, to your initials or business short code, to a branch or location identifier, or even to a product line marker, whatever helps you organise and recognise your invoices at a glance. For example, a designer might use her initials, a multi-branch shop might use a code for each outlet, and a business with separate verticals might prefix each one differently. The only things to keep in mind are the GST constraints: the entire invoice number, prefix included, must stay within sixteen characters and use only letters, numbers, hyphen, dash and slash, so a long prefix leaves less room for the year and the running number. It is also wise to keep your prefix scheme stable through a financial year rather than changing it midway, since a consistent format makes reconciliation and auditing straightforward. Set your chosen prefix in the field, and the generator will apply it to every number in the sequence.

If you cancel an invoice, the correct approach under GST is to keep the cancelled invoice number in your records and mark it as cancelled, rather than reusing the number for a different invoice or deleting it to close the gap. The reason is that your invoice series must remain consecutive and each number unique within the year, so a missing or reused number raises questions during reconciliation and scrutiny. By retaining the cancelled number and noting clearly that it was cancelled, you preserve an unbroken, auditable sequence: anyone reviewing your books sees that the number was issued and then voided, with no doubt about a hidden or duplicated invoice. Depending on the situation and timing, you may also need to issue a credit note or follow the prescribed cancellation process for invoices already reported in your GSTR-1, so it is worth checking the correct procedure with your accountant for your specific case. This generator helps you plan a clean series, but handling cancellations properly within that series is part of disciplined record keeping that keeps your numbering compliant.

No, the invoice numbers are generated entirely within your own browser, and none of your inputs, the prefix, financial year, start number, padding or count, are sent to us or any third party. The JavaScript on the page builds the sequence locally on your device, so your numbering scheme stays private and the numbers appear instantly without any network request. There is no account, no login and no stored history, which is also why the tool cannot remember your last used number between visits, as covered in another answer. The practical upshot is that you can plan and copy invoice numbers freely without privacy concerns, but you should copy any numbers you want to keep, since nothing is preserved once you change the inputs or close the tab. This local-only design also means the generator keeps working after the page has loaded even if your connection drops, because all the logic runs on your own device rather than on a remote server, making it both private and reliable for quick numbering tasks.