If you have opted for Composition Scheme under GST rules, you can easily manage the same in Book Keeper. Please check below details.
Firstly, you need to 'Enable Composition Scheme' under Settings > Company Settings.
Now, let's create a purchase transaction from a Registered Supplier.
For this, create your supplier account and select its registration type as "Regular". Also make sure that you have added Default Tax Rates of your inventory items.
Create a purchase transaction and apply tax to it. Once you have created a purchase, then please check Profit & Loss and Balance Sheet report.
In Composition Scheme, taxes are calculated as an expense and not as a liability. So the figures of Duties and Taxes will be shown under Profit and Loss report and not in Balance Sheet report.
Also you can check the Inventory Item detail report, cost has been calculated on the purchase value including tax as it is not the liability and will be treated as an expense. So, tax is included in purchase cost.
Now we will create a Sales voucher. In the below pic while creating invoice you don't need to apply tax. Just enter the quantity and rate and save it. Also while creating invoice, heading of "Bill of Supply" will automatically come.
Now we will check Inventory Item Details report. Invoice value of 2000 has been created. Purchase voucher is also there for Rs 1000+18%= 1180
So the cost will be calculated on 1180 because '180' which is charged for tax is not a liability and is an expense for us.
Moreover, Sales Register report shows 1180 as cost too.
If Composition Scheme is not enabled, cost has been calculated excluding tax because tax is a liability and thus not included in the preparation of Cost.