Balance owed

Need to update an app for work and it’s saying I have a balance.

OK, so see -> Check your Apple ID balance -> Check your Apple ID balance – Apple Support (UK)

Over $600 I know it was my child and I can’t afford to pay it now.

Your message is a bit confused / unclear.

What do you mean by that?

Is your Apple ID balance over $ 600?

Or has your child buy stuff over $ 600?

If you can’t afford to pay it now, don't buy anything.

See -> Request a refund for apps or content you've bought from Apple – Apple Support (UK)

If you have requested a refund, you must wait until Apple has approved. Then you will receive a message from Apple.

Refunds are not guaranteed. For more information, see the Terms & Conditions.

Is there any way to update the app?

If you want to make purchases or update apps, including free apps, you need to update your payment method or add a new one. 

Or do you know if they allow you to make payments?

Yes, if you purchase a paid app, you have to pay.

If you have secured your iPhone with a passcode, then your child will not have access to your iPhone, right?

Check ⤵️

Manage App Store purchases, subscriptions, settings, and restrictions on iPhone

Manage App Store purchases, subscriptions, settings, and restrictions on iPhone – Apple Support (UK)

Prevent in-app purchases from the App Store

Prevent in-app purchases from the App Store – Apple Support (UK)

Require a password for App Store and iTunes purchases

Require a password for App Store and iTunes purchases - Apple Support

Click here for more support and assistance.