Non-payment of salary for 18 months. What to do?

I have an unlimited contract since October 2019 with a company registered in DMCC Dubai.

I did not receive any wage (basic salary, bonus, accommodation allowance, business expenses reimbursement) since March 2020 (18 months) and no health insurance coverage since October 2020. The company is just promising.

The company decided first to reduce salaries by 50% due to Covid for three months (Apr-Jun 2020) with my acceptance. After that, they continued with the same reduction without my agreement. But even with that, no salaries are paid. The total amount due is above 500,000 USD.

I was obliged to leave UAE in November 2020 because of no income. It has been agreed and accepted by the company to work remotely.

I was also obliged to go back to Dubai at my expense every 6 months in order not to lose the visa.

Now, I have a job offer in another country starting in Oct 2021.

How to proceed with my company?

How to inform them?

Would I resign and file a claim later or file a claim immediately without resignation?