NIT check digit: what it is and how DIAN calculates it

The verification digit, or DV (dígito de verificación), is the single number after the hyphen in a Colombian NIT, like the 4 in DIAN's own NIT, 800.197.268-4. It is calculated from the other digits, so it works as a quick check that the number was typed correctly. It does not tell you whether the company is real. The NIT check digit calculator works it out for you, and this guide shows the maths behind it.

What the NIT is

The NIT (Número de Identificación Tributaria, or tax identification number) is how DIAN, Colombia's tax and customs authority, identifies each taxpayer (Estatuto Tributario art. 555-1; the Estatuto Tributario is Colombia's tax code). Companies have their own NIT. People registered in the RUT, the tax registry, use their cédula (national ID card) number as their NIT, with a verification digit added.

A NIT is usually written with dots every three digits and the DV after a hyphen. The dots are only there to make it easier to read. The hyphen matters: the digit after it is not part of the number, it is calculated from it. Two real, public examples:

• DIAN: 800.197.268-4
• Banco de la República, Colombia's central bank: 860.005.216-7

How the digit is calculated

The method DIAN uses is a weighted sum followed by the remainder of a division by 11 (a "modulo 11" check). Step by step:

1. Take the number alone, without dots and without the DV.
2. Multiply each digit by its weight, from right to left. The weights are, in order: 3, 7, 13, 17, 19, 23, 29, 37, 41, 43, 47, 53, 59, 67, 71. The last digit is multiplied by 3, the one before it by 7, the one before that by 13, and so on.
3. Add up all the products.
4. Divide the sum by 11 and keep the remainder, the amount left over.
5. Turn the remainder into the digit. If the remainder is 0 or 1, that is the digit. Otherwise, the digit is 11 minus the remainder.

The weights are the same for every NIT, whether it belongs to a company or to a person.

A worked example

Take 901.234.567, an invented NIT for the invented company tienda-ejemplo.co. Reading the digits from right to left:

Digit	Weight	Product
7	3	21
6	7	42
5	13	65
4	17	68
3	19	57
2	23	46
1	29	29
0	37	0
9	41	369
Sum		697

697 divided by 11 is 63, with 4 left over, because 63 × 11 is 693. The remainder is 4, not 0 or 1, so the digit is 11 − 4 = 7. The full NIT is 901.234.567-7.

Notice the zero. Its product is 0, but it still takes its place and its weight. If you skipped it, every digit to its left would move onto a different weight and the sum would change.

How to check a NIT with the calculator

1. Type the number. Open the NIT check digit calculator and type the NIT or the cédula number, with or without dots.
2. Add the digit you were given, if you have one. Type it after a hyphen, like 800.197.268-4. The calculator says whether that digit is right, and if it isn't, which digit it should be.
3. Open the step-by-step table. It lists each digit, its weight and its product, then the sum, the remainder and the rule applied, the same as the table above. It's a good way to follow the maths on your own number.
4. Copy the result. Buttons copy the digit alone or the full NIT with its digit.

The calculation runs in your browser, and the number you type isn't sent anywhere. There are also buttons with the NITs of a few public institutions, DIAN among them, so you can see a real example.

What a correct digit proves, and what it doesn't

A correct DV only proves that the number was typed right. It does not prove that the company exists, that the NIT belongs to the company named on an invoice, or that the company is up to date with DIAN. Anyone can calculate a valid digit for any number with the five steps above, including someone preparing a fake invoice or inventing a supplier.

To check whether a company exists and is up to date, look it up in the RUES (Registro Único Empresarial y Social, Colombia's business registry) or check with DIAN. Do that once for every new supplier or client, before the first payment or invoice.

If you get a message about your NIT or RUT that asks you to click a link or open a file, read the guide on fake DIAN emails first.

Where the digit matters

• Electronic invoices. Electronic invoicing systems validate the DV, so a wrong digit is caught there.
• Your records. When you add a supplier or a client to your accounts, check their NIT and digit once with the calculator.
• Your own details. When a client asks for your NIT, give the number and the DV together, separated by a hyphen.

Common mistakes

• Typing the DV as part of the number. Without the hyphen, 8001972684 is a different, ten-digit number, and the calculator gives the digit for that number, not for yours.
• Replacing the last digit of the cédula with the DV. The DV is added after the full number; the cédula number stays whole.
• Dropping a zero. Every digit, zeros included, has its own weight.
• Treating a correct digit as proof. It proves the typing, not the company.

Quick checklist

• I separated the DV from the number with a hyphen.
• I checked the digit with the calculator or by hand.
• For a new supplier or client, I looked the company up in the RUES or with DIAN.
• My invoices show my NIT with its correct DV.

This is a guide, not legal or tax advice. For anything that depends on a NIT or a RUT in your business, the payroll department or a contador (a certified accountant) has the final word.

Frequently asked questions

Does my cédula have a check digit?

When you're registered in the RUT, your NIT is your cédula number plus a DV, calculated with the same method as any other NIT. The calculator accepts a cédula number too.

What happens if the remainder is 0 or 1?

Then the digit is the remainder itself, 0 or 1. You only subtract from 11 when the remainder is between 2 and 10. That's why the DV is always a single digit, from 0 to 9.

The digit is correct. Does that mean the company is real?

No. It only means the number was typed right. Look the company up in the RUES or check with DIAN.

Why does my invoicing system reject a client's NIT?

Electronic invoicing systems validate the DV. Check the number and the digit with the calculator, and look for the mistakes above. If the number and the digit match, ask your client to confirm their NIT.

Try it

• 7.1NIT check digitCalculate or check the DIAN verification digit (DV) of a Colombian NIT or cédula with the modulo 11 formula, and see the calculation step by step.