Tally TDL Add-on Not Working? Fixes, Edits and GST Tweaks

It worked fine last month. Then Tally updated, and now the invoice prints without the transport column, or the report your manager checks every morning shows nothing at all. Who do you call?

Most people in this spot don't need a new add-on. They need a small, careful repair of the one they already have. This article is about those small jobs: what's usually wrong, what you can check yourself, and when to hand it over.

Start with a five-minute self-check

Before paying for any fix, rule out the simple causes.

1. Is the TDL actually loaded? In Tally Prime, check the TDL and add-on settings. A moved or renamed file just stops loading.
2. Did the file path change? Copying the Tally folder to a new PC often leaves the path pointing at the old one.
3. Did the Tally release change? Updates from ERP 9 to Prime, or between Prime releases, are the most common cause of breakage.
4. Are two add-ons fighting? Switch one off at a time and see if the problem disappears.
5. Is the TDL file the original? Some files are protected and can't be edited by anyone but the original author.

If none of these explain it, the code itself needs attention.

What counts as an add-on modification

This service covers changes to existing TDL work, not building from scratch. Typical examples:

• Fixing a bug or error shown on screen after loading the add-on.
• Adding a field to a sales invoice, such as vehicle number or e-way bill reference.
• Tweaking GST-related display, for example showing HSN summary differently.
• Changing a print format: column widths, a company logo area, extra declaration text.
• Adjusting a report's columns or filters.

Editable source versus locked files

This is the point people discover too late. A TDL file is either readable source (a .tdl file you can open in a text editor) or a compiled or protected version (often .tcp). We can edit the first. We can't legitimately open and rewrite the second without the author's permission, and we won't try to crack one.

If you only have a protected file, the honest options are: ask the original developer for source, ask them to make the change, or have a fresh version built, which is a different and bigger job.

GST tweaks: handle with care

Invoice changes touching GST need extra caution. A pretty print format that drops the place of supply or misprints a tax rate will cost more to untangle later than it saved.

Our habits for GST-related edits

• We change the display and layout only and don't alter how tax is calculated unless you ask and understand the effect.
• We test with at least one intra-state and one inter-state sample.
• We suggest you show the final print to your CA before using it for live bills.

The rules themselves change from time to time, so please verify current requirements with your tax adviser. We do the Tally side, not the tax advice.

What it costs and how long it takes

Tally TDL Add-on & Modification is listed from ₹4,500, with delivery in about 3 days. A single field or a print tweak fits that comfortably. Debugging an old add-on whose logic nobody remembers can take longer, because the first hour is just reading and understanding. We'd tell you that after looking at the file, before you commit.

There aren't separate package tiers on the service, so the price is set by what the job really involves.

When a rebuild is smarter than a repair

Sometimes patching an old add-on costs more than replacing it. If the file was written for ERP 9 and you've moved to Prime, if three different people have edited it over the years, or if every fix creates a new bug, a clean rewrite can be cheaper over time. We'll give you our honest view after reading the source. If a repair is the cheaper road, we'll take it. If not, we'll say so and point you to our custom TDL service.

Also keep a habit: save a dated copy of the working TDL before any edit. Name it something obvious. That one habit has rescued more offices than any clever debugging.

How we handle this at DegitalService

Send us the TDL file, your Tally version and a screenshot or short description of what's wrong or what you want changed. We review the source, tell you whether it's editable, and give a clear price and timeline. We work on a copy, return the updated file with notes on what changed, and help you load it correctly. Take a backup of your company data first, please. It costs nothing and removes most of the risk.

The service page has the summary. For a quick question about your specific file, use our contact page. Or you can order directly.