Examples of the impact the 1.3 percent cost-of-living increase announced today will have on the monthly checks received by average Social Security beneficiaries and on other Americans in 1999:

_Retired worker: benefits will increase to $780 from $770.

_Retired couple, both receiving benefits: check will rise to $1,310 from $1,293.

_Maximum retirement benefit: rises to $1,373 from $1,342.

_Maximum after-retirement earnings that will not trigger benefit reductions: rises to $15,500 a year from $14,500 for people 65 to 69 and to $9,600 a year from $9,120 a year for early retirees.

_Widowed mother and two children: benefits up to $1,554 from $1,534.

_Elderly widow or widower living alone: benefits up to $749 from $740.

_Disabled worker: benefits up to $733 from $724.

_Disabled worker with spouse and children: benefits up to $1,217 from $1,202.

_Maximum Supplemental Security Income (SSI) benefits for an individual: up to $500 from $494.

_Maximum SSI benefits for a couple: up to $751 from $741.

_For working Americans, the maximum annual earnings subject to the 6.2 percent Social Security payroll tax will rise to $72,600 from $68,400. The employer also pays a 6.2 percent tax for each worker.