To get information about billing plan settings of current user (billing plan name, balance, days left, available services), account and combined settings, use the command core/get_account_data:

svc=core/get_account_data&params={"type":<int>}

Types of response:

• 1 – minimal information, usually required to estimate the state of logged user;
• 2 – detailed information with combined, personal and billing plan settings.

Minimal information:

{
	"plan":<text>,			/* billing plan name */
	"enabled":<int>,		/* state: 0 - blocked, 1 - active */
	"​created":<​uint>,​		/​* creation time (unix time) */
	"flags":<uint>,			/* billing plan flags */
	"balance":<text>,		/* balance (with currency) */
	"daysCounter":<int>,		/* days counter */
	"services":{			/* services list */
		<text>:{			/* name */
			"type":<int>,		/* type: 1 - on demand; 2 - periodic */
			"usage":<uint>,		/* quantity of active resources of current service */
			"maxUsage":<int>	/* maximal quantity of resources */
		},
		...
	},
	"dealerRights":<int>,		/* allow using dealer rights for current billing plan: 0 - no, 1 - yes */
	"subPlans":[<text>],		/* array of subplans */		
	"​switchTime":​<uint>​		/​* time of switch "​enabled" param​ */ 
}

Detailed information:

{
	"plan":<text>,			/* billing plan name */
	"enabled":<int>,		/* state: 0 - blocked, 1 - active */
	"flags":<uint>,			/* flags - duplicates the same flags from billing plan settings (see the "plan" field below) */
	"balance":<text>,		/* balance (with currency) */
	"daysCounter":<int>,		/* days counter */
	"settings":{			
		"balance":<double>,		/* balance */
		"plan":{			/* billing plan settings */
			"flags":<uint>,		/* billing plan flags */
			"blockBalance":<int>,	/* block balance */
			"denyBalance":<int>,	/* deny balance */
			"minDaysCounter":<int>,	/* minimum days counter */
			"historyPeriod":<int>,	/* history period to store messages, in days (if 0 - unlimited) */
			"services":{		/* services list */
				<text>:{		/* name */
					"type":<int>,		/* type: 1 - on demand; 2 - periodic */
					"usage":<uint>,		/* count of used items of a type */
					"maxUsage":<int>	/* maximum allowed items of a type */
					"cost":<text>,		/* cost table */
					"interval":<int>	/* reset interval: 0 - none, 1 - hourly, 2 - daily, 3 - weekly, 4 - monthly*/
				},
				...
			}
		},
		"personal":{			/* personal (account) settings */
			...			/* has the same format as billing plan settings */
		},
		"combined":{			/* combined settings (overlapping billing plan and account settings) */
			...			/* has the same format as billing plan settings */
		}
	},
	"siteAccess":{
			"<service_name>":"<dns_name>",		/* where key is service name and value is dns-name */
			...
	},
	"dealerRights":<int>,	/* allow using dealer rights for current billing plan: 0 - no, 1 - yes */
	"subPlans":[<text>]	/* array of subplans */
}

You can find available values of billing plan and account flags, as well as list of services in the chapter Detailed information about account.