Accounting & GST Applicability

Record it as commission or sales, which ever applies. If commission, 

Unfortunately, Commission Income is Taxable too and it is deducted at the source by the person paying the commission. Tax on Commission Income in India Commission Income is Taxed at the rate of 5% of the total amount received as per Section 194 H of the Income Tax Act. 

Now it cannot be sales because principal-agent relationship exists and risks and rewards are not borne by X. 

A1 : The amount received is on behalf on company Y. So Debit bank and credit company Y ( Current liabilities ).

Company Y would generate the invoice to end consumer and received the payment from third party company X

A2 : company X would generate its commission invoice + 18% gst. which would be adjusted and balance amount would be paid by x to y

X WILL BOOK ONLY COMMISSION SALES AMOUNT TO Y

Y WILL BOOK CAR BOOKING SALES TO END CONSUMER
Y WILL BOOK COMMISSION EXPENSE TO X

THERE IS NO SCOPE FOR TDS DEDUCTION IN HANDS OF Y as X has all the money with it. THERE ARE ENOUGH CASE LAWS WHICH WOULD ALLOW COMMISSION EXPENSE DEDUCTION UNDER INCOME RAX LAW EVEN WITHOUT TDS compliance.

Please convey a like to this answer if it was helpful.

I heard they are planning to include taxation transactions into reporting to give more weightage to reporters and it is easy. Then, taxation will consists of tax planning, income tax and corporate tax issue.