# Set up your certificates Source: https://help.mucka.ai/gas-certs/set-up-gas-and-oil-certificates Category: Certificates Last updated: 2026-08-28 > Tell Mucka whether you work with gas, oil, air conditioning or a mix, and add the registration numbers that print on every certificate. Certificates have their own settings: what you work with, and the registration numbers that appear on every record you issue. You set them once and forget about them. ## Open the settings Three ways in, whichever you're nearest: 1. **On the certificates page.** On a computer, tap **Settings** next to **New Certificate**. On your phone, tap the cog next to the search box and choose the **Settings** tab. 2. **From the Skills page.** Go to [**Skills**](/skills) and tap the cog on the **Certificates** card. 3. **When you install it.** The same settings open the first time you add the skill. ## Choose what you work with Three switches: **Gas**, **Oil** and **Air Con**. Turn on whichever your business does, and leave the rest off. What that changes: - **The New Certificate list.** A gas-only business never sees oil or air con forms, and the other way round. Work with more than one and tabs appear at the top of the list so you're only ever looking at the forms for one trade. - **Which numbers you're asked for.** Gas asks for Gas Safe, oil asks for OFTEC, air con asks for your F-Gas certification. The section is called **Certificates** in the menu and at the top of the page, whatever you pick. If you've been using Mucka for gas certificates already, nothing has changed for you: you're set to gas, and the rest stays out of the way until you turn it on. Only an owner or admin can change this one, since it decides what the whole team sees. The remaining oil forms (CD/10, CD/14 and TI/133D) are being built now. Turning oil on today adds them to your list as each one is finished, so you'll see them the moment they land. ## Add your registration numbers Underneath, add the numbers that print on your paperwork. - **Business registration.** Your Gas Safe registration number, your OFTEC registration number if you work with oil, and your company F-Gas certification number and body (REFCOM, Bureau Veritas or Quidos) if you do air con. - **Engineer registrations.** For each person on the tools: their Gas Safe licence number and its expiry date, their OFTEC technician number for oil, and for air con their F-Gas certificate number, category and ACRIB SKILLcard number. An engineer without **manage team** only sees their own row, so anyone can put their own licence in without waiting on the office. The same numbers also sit on each person's own record, under [**Settings → Team → People**](/settings/team/team) — tap someone and they're there with their mobile and their role. It's the same information either way, so put it wherever you happen to be. If you do air con, there is also a **Great Britain / Northern Ireland** choice. GB and NI run separate F-Gas regimes with the same rules today; telling Mucka which one you are under now means nothing changes for you if they ever drift apart. ### The three trades work differently here, on purpose **Gas Safe numbers are required.** You can't approve a gas certificate until the business registration and the engineer's licence are on file, and not under a licence that has expired. That's the law, not a Mucka rule, and the card is renewed each year with a new number, so update both when it's replaced. **OFTEC numbers are optional.** Oil isn't a licensed trade the way gas is, so a missing OFTEC number never stops you issuing a certificate. Put it in and it prints on your oil paperwork. Leave it out and everything still works. **F-Gas numbers are required where the law requires them.** Working on a system that holds an F-gas refrigerant legally needs company and engineer F-Gas certification, so those certificates won't approve without the numbers. On a system running propane, CO2 or an HFO the same numbers are optional and simply print when you have them. The ACRIB SKILLcard is always optional. ## Change it later Nothing here is locked in. Turn a trade on the month you take on your first contract for it, or off again if you drop it, and the lists follow along. Certificates you've already issued are untouched: your archive keeps everything you've ever done, whatever the switches say today.